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In Brief
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- Both lesbians and gay men often have a history of cross-sex-typed behaviors: little boys becoming infatuated with their mother's makeup kit; little girls enamored of field hockey or professional wrestling.
- Prehomosexual boys tend to be more attracted to solitary sports such as swimming, cycling and tennis than they are to rougher contact sports such as football and soccer.
- Children who show pronounced sex-atypical behaviors may have more of a genetic loading to their homosexuality.
Excerpted from Why Is the Penis Shaped Like That? … And Other Reflections on Being Human, by Jesse Bering, by arrangement with Scientific American/Farrar, Straus and Giroux, LLC (North America), Transworld Ltd (UK), Jorge Zahara Editora Ltda (Brazil). Copyright © 2012 by Jesse Bering.
We all know the stereotypes: an unusually light, delicate, effeminate air in a little boy's step, an interest in dolls, makeup, princesses and dresses, and a strong distaste for rough play with other boys. In little girls, there is the outwardly boyish stance, perhaps a penchant for tools, a square-jawed readiness for physical tussles with boys, and an aversion to all the perfumed, delicate trappings of femininity.
These behavioral patterns are feared, loathed and often spoken of directly as harbingers of adult homosexuality. It is only relatively recently, however, that developmental scientists have conducted controlled studies to identify the earliest and most reliable signs of adult homosexuality. In looking carefully at the childhoods of gay adults, researchers are finding an intriguing set of behavioral indicators that homosexuals seem to have in common. Curiously enough, the age-old homophobic fears of many parents reflect some genuine predictive currency.
J. Michael Bailey and Kenneth J. Zucker, both psychologists, published a seminal paper on childhood markers of homosexuality in 1995. Bailey and Zucker examined sex-typed behavior—that long, now scientifically canonical list of innate sex differences in the behaviors of young males versus young females. In innumerable studies, scientists have documented that these sex differences are largely impervious to learning. They are also found in every culture examined. Of course, there are exceptions to the rule; it is only when comparing the aggregate data that sex differences leap into the stratosphere of statistical significance.
The most salient differences are in the domain of play. Boys engage in what developmental psychologists refer to as “rough-and-tumble play.” Girls prefer the company of dolls to a knee in the ribs. Toy interests are another key sex difference, with boys gravitating toward toy machine guns and monster trucks and girls orienting toward baby dolls and hyperfeminized figurines. Young children of both sexes enjoy pretend play, but the roles within the fantasy context are gender-segregated by age two. Girls enact the role of, say, cooing mothers, ballerinas or fairy princesses, and boys prefer to be soldiers and superheroes. Not surprisingly, therefore, boys naturally select other boys for playmates, and girls would much rather play with other girls.
So on the basis of some earlier, shakier research, along with a good dose of common sense, Bailey and Zucker hypothesized that homosexuals would show an inverted pattern of sex-typed childhood behaviors—little boys preferring girls as playmates and becoming infatuated with their mother's makeup kit; little girls strangely enamored of field hockey or professional wrestling—that sort of thing. Empirically, the authors explain, there are two ways to investigate this hypothesis, with either a prospective or retrospective study. Using the prospective method, young children displaying sex-atypical patterns are followed into adolescence and early adulthood so that their sexual orientation can be assessed at maturity.
This method is not terribly practical for several reasons. Given that a small proportion of the population is homosexual, prospective studies require a large number of children. This approach also takes a long time, around 16 years. Finally, not a lot of parents are likely to volunteer their children. Right or wrong, this is a sensitive topic, and usually it is only children who present significant sex-atypical behaviors who are brought into clinics and whose cases are made available to researchers.
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32 Comments
Add CommentHi Jesse,
Reply | Report Abuse | Link to thisI've got no reason to doubt what you write here and support with statistics, but I have a couple of questions about the statistics you quote:
In Drummond's study, you write "the odds of these [25] women reporting a bisexual or homosexual orientation were up to 23 times higher than would occur in a general sample of young women." What do you mean, especially by "up to"? My library doesn't have the journal, but according to the online abstract, 6 of the 25 women studied, or 24%, were bisexual or homosexual in orientation. That gives a 95% confidence interval of from about 10% to 45% for the actual proportion of lesbian/bisexual orientation among girls referred for assessment for GID (60% of whom met the GID diagnostic criteria).
Calling this "up to 23 times higher than would normally occur…" sounds like you quoting the upper limit of a confidence interval. I hope you're not, because that would be a terribly misleading interpretation to make. If it were ok to do this, every study would be small: the smaller the study, the more amazing the findings could be, even if the study found nothing! For example, a study that found 0 prelesbians out of 25 in a group of GID kids could be pitched as finding an "up to 15%" of the study population were lesbian, even though none were found in the sample. A study that found 0 out of 10 could say "up to 30%."
You also write that "[T]he same holds for gay men," and that "Bailey and Zucker [conducted] a retrospective study [that] revealed that 89 percent of randomly sampled gay men recalled cross-sex-typed childhood behaviors exceeding the heterosexual median."
You don't name a paper by Bailey and Zucker in your references, but one in Developmental Psychology contains a similar statistic: "89% of gay men exceeding the heterosexual median." Is that the paper? It isn't a study, it's a meta-analysis (including several of Bailey's own studies, as well as other same-author papers, which are potential sources of bias), and the participants are not randomly sampled. This meta-analysis also looked at both men and women, but found less of an effect in women. You look at least superficially to be cherry-picking here - quoting one study for men, then because that study shows less effect for women, choosing a different study to quote for women (failing to mention its tiny sample size, and then exaggerate with "up to.")
I don't think your argument would be any weaker if you'd given more careful interpretations of these papers, so maybe I'm missing something.
So Jesse Bering tells us sissy boys and butch girls are more likely are more likely to grow up to be gay or lesbian. Does that tell us more than a hypothetical study that told us that math nerds are more likely to grow up to be Asian? Such a study would tell us very little about Asians or math nerds.
Reply | Report Abuse | Link to thisMasculinity and femininity are social constructs. A man may be more or less masculine or feminine and more or less gay or straight. Similarly for a woman. Bering's article only correlates some childhood gender expression with later sexual orientation. Do the statistics apply equally to masculine gay men and feminine lesbians as to feminine gay men and masculine lesbians? Or is he simply saying that somewhat feminine boys are more likely to grow up to be somewhat feminine men, many of whom are gay?
Since most of the studies cited were retrospective, how do they control for confirmation bias. As a gay man, I have tried to search out the antecedents of my homosexuality. How could I not have known earlier? A masculine straight man might suppress memories of childhood gender non-conformity because they are inconsistent with his current self-image.
Baily hopes to counter this bias by citing a study which he and others published in Developmental Psychology in 2008. But his results (p. 50) indicate that the homosexual subjects of his study were feminine gay men and masculine lesbians (except for one feminine lesbian, who was excluded as an anomaly). It is as though masculine gay men and feminine lesbians cannot exist, because they would refute his thesis. Bering reinforces old stereotypes by excluding data that would contradict them.
The author of this article should be congratulated for the courage and wisdom to write an article, which enlighten us on "sexual orientation and how it is influenced by environmental, biological and heridatary factors. This also raises an important question, how should boys and girls be raised?
Reply | Report Abuse | Link to thisMy overall reaction to this article is one of grave concern since human development is not just a simple matter of genes and environment. Even the front cover is reminiscent of tabloid journalism and fear mongering. It should not matter what the sexual orientation of a young child is unless it causes the child long term distress and requires medical attention.
Reply | Report Abuse | Link to thisUnfortunately it is not all that hard to imagine a number of religious groups around the world using this article with all of its shaky and unconvincing data as proof supporting their belief structures. Most of humanity is already being filtered using out dated modes of thinking. For example "race"; the Human Genome project showed that there is only one race "Human"
Does this mean that we should force male children who might become homosexuals to play football or female children to learn to be a future mother, as opposed to allowing them to find their own physical and mental talents? I think that this is the wrong approach to raising any child.
We should let them be children first before we start to filter and categorize them onto "straight", "gay", "other" and love them with out any conditions attached including "evolutionary homophobia".
As a human society, we should have evolved beyond all of this. With a global population of more that 7 billion humans we should be more concerned with our long term survival that which ones will create the next generation.
If you want to know if your son is gay, wait until he's two or three years old and ask him if he likes the Three Stooges. If he hates the Three Stooges, he's gay. If he's indifferent toward the Three Stooges, he's bisexual. If he loves the Three Stooges, he's hetero. You can ask your daughter the same question, only the responses are reversed. If she loves the Three Stooges she's gay. If she hates the Three Stooges, she's straight.
Reply | Report Abuse | Link to thisIt works. It really, really works.
This is exactly what I was thinking, this whole article made me flinch. Being straight doesn't preclude an understanding of gender and sexual nuance, and apparently being gay doesn't either.
Reply | Report Abuse | Link to this*being gay doesn't require it either (on phone, oops).
Reply | Report Abuse | Link to thisYes, masculinity and feminity are societal constructs. How much of binary sexuality -- you have to be either gay or straight -- is a result of our culture's disdain for people who do not conform to traditional gender roles? The impact of hierarchical, patriarchal "norms" cannot be overstated. You don't conform to gender stereotypes? Great -- the only option for you is to be gay or lesbian. This reinforces the hierarchy.
Reply | Report Abuse | Link to thisThe other thing that bothers me about this construct is the notion of heterosexuality as "true north". Given the many admonitions against exploring same-sex attractions, there is no way to make accurate predictions. Is it only ok to be gay if it's genetic?
What about us bisexuals? Or do we get to be excluded once again as "anomalies"? Kinsey believed that sexuality was more of a gray-scale than black & white. So what do these findings say if that is true? I seriously get tired of both gay & straight communities seeing this issue as black and white. Maybe the little girl who plays with trucks is NOT lesbian. Maybe she's bi, but because we are SO concerned with labeling everyone's sexuality in black & white terms that she spends her whole life confused about her sexuality, knows she likes boys AND girls, but then realizes it's easier to get through life if you conform. Or she rebels against people telling her what to be and she shuns girly stuff. There is a huge biological component, in my opinion (and I do realize it's ONLY one opinion), but there are also serious societal and psychological factors that come into play with sexuality. I realize black & white makes things easier, but life just doesn't work that way.
Reply | Report Abuse | Link to this@Dolmance: I hated the Stooges as a child and am gay. But I love them now as an adult. Does that make me now straight? lol. Actually, as a kid, I hated the violence - and although I still find it uncomfortable, I now understand their comedic genius.
Reply | Report Abuse | Link to thisInteresting article, especially since growing up I loved to play with dolls, especially my sister's Barbie dolls (I still tease my mother and grandmother about the Christmas they both bought me Ken dolls - see, mom, it was your fault.) I found the comments to be better - especially tomthurston's. This study would be more complete and accurate if they included ALL gay men and women, not just stereotypical effeminate/butch groups. I'm sure the results would be very different, and would like to see a break down of behaviors of more masculine gay men (and they do exist.)
Let's guess about a person sex based on what they like.
Reply | Report Abuse | Link to thisMaybe some boys liked Barbie dolls big breasts and sexy shape, the whole approach is very silly. Let kids learn for themselves what they like. We are what we are!
Ditto on all the bisexuality references, sexuality is NOT an either or proposition. Ditto on the references to fem guys and butch girls, might as well do a follow up to see if the fem guys are also "bottoms"... what strange and bizarre categories we have invented. Are there such things as "passive" orgasms? No. A question regarding the worldwide reference to typical boy and girl play preferences... is this a reference to rough and tumble play, same sex playmate preferences (and at what ages), or "big trucks" and "hyper sexualized dolls"? Yes, all cultures throughout history have their examples of men taking on their cultures female roles and visa versa, but that doesn't measure the full range of bisexual and homosexual expression within those cultures. We don't have an accurate measure of our own modern cultural expressions of bisexuality and homosexuality, we can't even agree on what percentile of men and women would fit into Kinsey's 1-6 scale, at any one point in their lives, let alone throughout their lifetimes. The title worries me as well, IS my child gay? How about "Is my baby gay?" or "Is my fetus gay?" Is this not sexualizing our natures way too early? Will my child grow up to enjoy same sex partners? Lets distort this even further and maybe reveal some gender role bias at the same time, Will my son grow up to enjoy housework? Will my daughter grow up and enjoy being the mechanic in our family? If boys who prefer girls company is an indicator of future same sex preferences, would someone please study how the "straight" boy child goes through a process of rejecting his boy buddies to "prefer" the company of women... or maybe he doesn't... continues to prefer the company of men and prefers sex with women... hmm... seems straight women are still pondering that one... bingo... that's why she has so many "gay" guys as her best friends... yeah right... the ones who played with her dolls.
Reply | Report Abuse | Link to thisDr Bering, I got the impression from reading your article that its purpose was more about revealing and using your own homosexuality as an "expert witness" contribution rather than any 'real' scientific revelation. This topic has had little scientific research, and what interest there is usually comes from the people willing to pay to find out how and if homosexuality can be prevented. In nature animals display distict behavior conforming to their male or female gender - these are not 'roles' animals play, it is what it is. Humans also act out in revealing ways, we are just simply more 'theatrical' in our options.
Reply | Report Abuse | Link to thisI found somewhat disgusting the tone of the article and also some comments in the discussion that homosexuality would be somehow "unwanted", "not preferred", a handicap or something to be "prevented".
Reply | Report Abuse | Link to thisPlease, allow children to grow up as they are, gay or straight and encourage them to find this and other personal characteristics for themselves. To me, this is plain homophobia disguised as "science".
I would rather see efforts directed to reducing discrimination faced by minorities than researching this kind of "science".
Quote: Please, allow children to grow up as they are, gay or straight and encourage them to find this and other personal characteristics for themselves.
Reply | Report Abuse | Link to thisAnswer: THAT is the same as you saying , "allow your child to grow up with diabetes and don't treat it".
If a child appears to be homosexual , it is hormones , and when treated , they recover.
"We believe that hypogonadotropic hypogonadism in juvenile hemochromatosis may be reversible by a consequent venesection therapy probably because treatment was intensive and promptly introduced at a young age."
http://www.ncbi.nlm.nih.gov/pubmed/16359978
"All patients with 'idiopathic' hypopituitarism should be screened for hemochromatosis"
"We recommend that iron studies are performed in all patients who present with hypopituitarism and normal pituitary imaging. This may lead to reversal of the hypopituitarism and avoid development of any systemic consequences of hemochromatosis"
http://www.ncbi.nlm.nih.gov/pubmed/18270843
Wow ironjustice - way to completely miss the point. Did you READ either of those studies? 1) The first one discusses ONE specific medical case (n=1 meaning ONE person, not a valid study to represent the masses of people who are queer) who responded to treatment for a condition that 2) has nothing to do with being gay, so far as I can tell. Queer people aren't sick - they are just different, and I just don't understand WHY that is such a problem for people. Different does NOT always = BAD. Quit the homophobism already - please?
Reply | Report Abuse | Link to thisQuote: Quit the homophobism
Reply | Report Abuse | Link to thisAnswer: You accuse me of bigotism on a Science list ? You got a problem. You had better stop your accusations of hate crimes there , I , we are getting tired of it.
I really dislike these kind of studies since they never seem to answer questions; too much wiggle room.
Reply | Report Abuse | Link to thisNo doubt some behavior tendencies may increase the probability of having certain sexual tendencies. But, I've had my confirmation biases challenged on too many occasions to take them seriously any longer. I have been acquainted with many men and women over the years who showed clear signs of being gay, only to find out differently. And, I've have seen the opposite. And, of course, the reality of being bisexual pretty much eliminates these simple observations as being good predictors.
I have no doubt that biological causes are at work here, some of which occur during fetal development and which either manifests itself by birth or as the child approaches puberty. I would also not be surprised if the environment evokes inherited evolutionary adaptations that change sexual tendencies since the animal kingdom shows quite a variety.
Quote: I would also not be surprised if the environment evokes inherited evolutionary adaptations that change sexual tendencies
Reply | Report Abuse | Link to thisAnswer: The evolutionary theory is this. Man is a herbivore eating meat. The outcome of this is ? Or would be ? Once one realizes man is a herbivore one would have to find out the results of said action of switching from herbivore to omnivore ?
First what would be the 'reasons' the animal is eating meat ? It would be either , there are no plants left to feed the population of herbivores , therefore cannibilism , or the population has gotten too large for the available plants ? No reasonable brain dead animal would CHOOSE to change its herbivoriousness ?Using reason , those two , would be the ONLY reasons an obligate herbivore-frugivore would eat meat ? Scientifically then the things to happen would be a cull , either by increased death or by turning the population gay. BOTH are happening due to the same thing. Meat eating leads to increased iron which leads to increased death , increased iron leads to hypogonadism , hypopituitism , gayness , etc.
The Herbivore Hypothesis.
Ironjustice: Sorry, I don't fully understand your reasoning or arguments. I do not see how they would be related to homosexuality in any way. Please, if you could clarify your point further?
Reply | Report Abuse | Link to thisI understood that you were presenting homosexuality as a disease (comparing it with diabetes) and claimed that you had a cure for it. That I would call homofobia.
@ironjustice: You're batting 1000 in making no sense (nonsense).
Reply | Report Abuse | Link to thisQuote: You're batting 1000 in making no sense (nonsense).
Reply | Report Abuse | Link to thisAnswer: I'm not sure which part or all don't you understand ? Saying someone is homophobic is like saying someone is a racist. Simple talking about , inequality of the races , is considered a 'hate crime' , according to law and University law. Therefore , when someone attempts to label me homophobic , we best know we are playing on the same field so to speak.
As to homosexuality caused by meat , if THAT is what you cannot understand ? The heme iron found in meat is absorbed at a very high rate and causes iron excess which causes endocrine disruption. Endocrine disruption is an underlying cause of homosexuality and other sexual abnormalities as evidenced by the use of DES in pregnancy and their giving birth to all different types of sexually abnormal children.
"The Presence of Gender Dysphoria, Transsexualism, and Disorders of Sexual Differentiation in Males Prenatally Exposed to Diethylstilbestrol: Initial Evidence from a 5-Year Study"
http://www.antijen.org/transadvocate/id33.html
@ironjustice: Your reference to http://www.antijen.org/ is interesting but seems quite misleading. The paper in particular by its own words seems to have little scientific basis. In any case, they admit their studies are "qualitative" and not "quantitative", so little can be said statistically about the prevalence of harm or transgender issues due to DES. In fact, DES seems their only concern so their sampling is limited those suspected of being affected by DES. And further, by their own words, the sample also consists of those who responded to their survey.
Reply | Report Abuse | Link to thisSorry, the studies by this group does not seem to have any scientific validity. The author of the paper you cite is the founder of this DES organization, he doesn't seem to have any expertise in this area, and has never written up research that passed refereed muster. He seems to have a PHD but it is in Education, not any level of the biological sciences.
A component of childhood behaviors unmentioned is the consistent finding of siblings choosing differing roles. Without the intent to write a referenced letter here, I would like to point readers toward deeper study of developmental choices and their relationship to social structures in the cultural styles in which we evolved, before recent urbanization and large populations shadowed the social usefulness of human variation.
Reply | Report Abuse | Link to thisLook to social anthropology and evolutionary psychology for exploration of both the utilitarian values of differing sexual orientations, and of more tolerance than those who would automatically politicize, presume.
To those involved with genetic and other heritability (of which there is a large component in homosexuality) I would also point toward some unpredictability due to environmental/epigenetic changes.
Having been involved in professions in which a strong mix of quite different homosexual individuals and varying heterosexual personalities, I'd hope that ganeralization would be avoided as much as possible wherever it is unfounded. This includes perceived need to defend sexual orientation as well as attack differences. To repeat, please go to studies of other cultures.
Some heterosexual males are rather predatory toward juveniles, as are some homosexuals. This varaiation, while having some evolutionary value during stresses upon small populations, is confounded in public perception of sexual variation, and I see some results of that confound in discussion here, as most cultures large and small did have a problem with that behavior.
Do remember that males evaluate reproductive capacity through physical attributes (as do females, with some exception), and that this evaluation can lead to preference for youthful-seeming traits. Some cultures and many parents have recognized a focus on as-yet nonadults as threatening. In small cultures we more often see a greater respect for individuality taught. This attribute works to the benefit of every individual of such societies, whether adult or child, through its obvious results.
Yes, xopher, some masculine-traited homosexually-oriented males were prized in some cultures and subcultures (by which I include military groups as professions across history). Moreover, the populations of prisons show that intimacy and other necessities of individuals in a social species, can sometimes be of greater import than specific sexual orientation.
I happen to be obligate heterosexual, although I exhibited some traits less-associated with heterosexual males than many.
Quote: iron found in meat is absorbed at a very high rate and causes iron excess which causes endocrine disruption
Reply | Report Abuse | Link to thisAnswer: This is an example of iron induced endocrine disruption.
"We examined 25 aplastic anemia patients (11 men and 14 women) diagnosed with transfusion-associated hemochromatosis at a single institution."
"Twenty-two (88%) of these 25 patients had at least one endocrine abnormality, and 12 had more than one abnormality. The most common pituitary hormonal deficiency involved the pituitary–gonadal axis; 54% of the total subjects had hypogonadotropic hypogonadism."
This article is a load of bollocks. The conclusions are spurious, the data sparse on the verge of being statistically meaningless and clearly invalidated by the cognitive biases and failed judgement heuristics applied by the researchers. Less than useless.
Reply | Report Abuse | Link to thisI looked in vain for mention here of all the masculine boys and feminine girls who turn out to be mostly or completely same-sex oriented as adults.
Reply | Report Abuse | Link to thisWhere do they fit into this theorizing? They don't, so they're ignored.
And how about the adult straight women who love rough-and-tumble sports, the adult straight men who love fashion? The fact that the vast majority of adult transvestites are heterosexual? The fact that ordinary men in some cultures seem very feminine to Westerners, and ordinary women in some cultures seem very masculine? They're all ignored, too. The caveats are very weak, and seem to be afterthoughts added when someone told the author "You've got to be kidding, that old canard was disproved long ago".
This article would be better published in "Gullible American" than "Scientific American".
I read the Three Stooges comment as a parody of the statistics quoted in the article. I was glad to see the informed response to the author's misuse of statistics.
Reply | Report Abuse | Link to thisExactly what is "sissy stuff"? (Quoting the thumbnail intro to the oh my god is your child gay article in the table of contents.) Girl stuff? Is that "sissy?" This word is charged with contempt. But the worst part of this article is the second paragraph: "These behavioral patterns are feared, loathed, and often spoken of directly as harbingers of adult homosexuality." Feared? Loathed? By whom? Jesse Bering? Not by this parent. I can't trust the work of an author who betrays this much repugnance for the human subjects being discussed.
Reply | Report Abuse | Link to this"If you want to know if your son is gay, wait until he's two or three years old and ask him if he likes the Three Stooges. If he hates the Three Stooges, he's gay. If he's indifferent toward the Three Stooges, he's bisexual. If he loves the Three Stooges, he's hetero. You can ask your daughter the same question, only the responses are reversed. If she loves the Three Stooges she's gay. If she hates the Three Stooges, she's straight.
Reply | Report Abuse | Link to thisIt works. It really, really works."
No it doesn't. I was crazy for the Three Stooges as a child and I am (and have always been) as gay as a picknick basket. Try again.
"whereas gay adults who were sex-typical as children might trace their homosexuality more directly to particular childhood experiences."
Reply | Report Abuse | Link to thisI'm one of those gay guys who grew up with 3 straight brothers, and has always been into "rough and tumble" playing as a kid, team sports as a high school and college student, and typical "guys" activities ever since. Almost all of my good friends have been straight guys. Yet, I can't recall ever thinking I was anything other than attracted to guys. And I certainly can't "trace my homosexuality more directly to particular childhood experiences." I'm not even sure what that means, but there weren't any specific events that I recall in my childhood that made me gay.
By contrast, I have a good friend that everyone just assumes from appearance, mannerisms and interests is gay. Nope, 100% straight. Obviously anecdotes aren't data, but the whole "childhood play predicts adult sexual orientation" theory seems to severely oversimplify what is probably a complex interplay of genetic, hormonal, and social factors.
I have a bachelor's and master's degree in sociology and am currently working on my PhD with a certificate in Gender Studies. A relative sent me a link to this article, and I have to say, it's extremely disappointing to read any publication with "science" in the title so blatantly misrepresent scientific knowledge on gender and sexuality.
Reply | Report Abuse | Link to thisThere's nothing scientifically canonical about "sex differences.” On the contrary, sociologists and psychologists have joked about renaming such inquiries "sex similarities research," on the basis that time and time again they've found more similarities than differences between genders. The study cited here from1995 is both outdated and widely criticized – hardly evidence of consensus on the matter. The "sex differences" hypothesis fails in part because of the ANOVA test (there are more differences within groups than between groups), so the claim about "statistical significance" on the aggregate is also inaccurate.
“The broad pscyhological similarity of men and women as groups can be regarded, on the volume of evidence supporting it, as one of the best-established generalizations in all the human sciences.” That’s from R. W. Connell’s “Gender: Short Introductions” (p. 60-66). Barrie Thorne's "Gender Play" is also a fantastic resource for understanding how children's sex-typical play behaviors are shaped by society and frequently challenged by children themselves. These two sources are legitimately canonical in the study of sex and gender. The consensus within these interdisciplinary fields is that all children cross gender boundaries and that there's no inherent link between gender performance and sexual orientation.
I can see the point the author is trying to make: "if it were possible to predict your child's sexual orientation, would you want to and why?" That's an interesting hypothetical and I can see that their intent is not homophobic... but the author is actually doing a lot more harm than good by distorting the research on gender, childhood, and sexual orientation to make that point. For example, the "common sense" idea that children who cross gender boundaries are gay has caused a lot coercive correction against children who are just doing what children naturally do. If these claims were scientifically valid, then these would be challenges we’d have to deal with. But denying scientific knowledge in favor of cultural myths has never done society any favors.