Clare Porac, a professor of psychology at Pennsylvania State University who studies handedness, explains.
Researchers who study human hand preference agree that the side of the preferred hand (right versus left) is produced by biological and, most likely, genetic causes. The two most widely published genetic theories of human hand preference argue that evolutionary natural selection produced a majority of individuals with speech and language control in the left hemisphere of the brain. Because the left hemisphere also controls the movements of the right hand--and notably the movements needed to produce written language--millennia of evolutionary development resulted in a population of humans that is biased genetically toward individuals with left hemisphere speech/language and right-hand preference. Approximately 85 percent of people are right-handed. These theories also try to explain the persistent and continuing presence of a left-handed minority (about 15 percent of humans).
The genetic proposal to explain hand preference states that there are two alleles, or two manifestations of a gene at the same genetic location, that are associated with handedness. One of these alleles is a D gene (for dextral, meaning ¿right¿) and the other allele is a C gene (for ¿chance¿). The D gene is more frequent in the population and is more likely to occur as part of the genetic heritage of an individual. It is the D gene that promotes right-hand preference in the majority of humans. The C gene is less likely to occur within the gene pool, but when it is present, the hand preference of the individual with the C gene is determined randomly. Individuals with the C gene will have a 50 percent chance of being right-handed and a 50 percent chance of being left-handed.
These theories of hand preference causation are intriguing because they can account for the fact that the side of hand preference of individuals with the C gene (most left-handers and some right-handers) can be influenced by external cultural and societal pressures, a phenomenon that researchers have documented. These theories can also explain the presence of right-handed children in families with left-handed parents and the presence of left-handed children in families with right-handed parents. If the familial genetic pool contains C genes, then hand preference becomes amenable to chance influences, including the pressures of familial training and other environmental interventions that favor the use of one hand over the other. The proposed genetic locus that determines hand preference contains an allele from each parent, and the various possible genetic combinations are DD individuals who are strongly right-handed, DC individuals who are also mostly right-handed, and CC individuals who are either right-handed or left-handed. These genetic combinations leave us with an overwhelming majority of human right-handers and a small, but persistently occurring, minority of left-handers.
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15 Comments
Add CommentPlease inform me if it is advicable to encourage my child age 3 to change from left hand to right hand before starting school?
Reply | Report Abuse | Link to thisMy baby is 6 months old and shows a preference to her left hand and seems to have more control of and coordination with her left hand. Her dad is left handed and I am right handed. Do you think she will be left handed?
Reply | Report Abuse | Link to thisI have a daugher, 16, who is left-handed. We did nothing to prevent her from being left-handed. She has adapted to this right-handed world and is capable of using her right hand almost as well as her left.
Reply | Report Abuse | Link to thisShe has the advantage particularly in soccer. It is more difficult for her opponents to defend or attack. She is capable on both feet.
My position is to let them be who they are. I consider it an advantage. I only wish my left was more useful.
My family has had a 50% of the C Gene. My oldest bro is right, next is Left, then right, then left, then right, then me... I'm left...
Reply | Report Abuse | Link to thisso... RLRLRL...
My family also seems to also have a higher chance of being cross-dominant.
Reply | Report Abuse | Link to thisI am left hand and their is nothing wrong with it i just feal more comfort using it
Reply | Report Abuse | Link to thisI come from a family of 7 children and 3 of the seven are left handed including myself. In chronological order it is the 3rd, 5th and 7th children born. My Mom is right handed and my Dad uses both hands but is dominant with his right hand. I have just a handful of nieces and nephews that are left handed the majority of them are right handed. My son uses both hands but like my Dad, he is dominant with his right.
Reply | Report Abuse | Link to thisi,am only lefty in my family.none of our fore fathers had been lefty.
Reply | Report Abuse | Link to thisI use my lefty in every feild.but it is very difficult for me to write or play with my right.
Please tell me should i try more &more to improve my rigqt or it will cause any harm to me both physically & mentally.
I consider myself left handed. I write left handed and eat left handed. Feeding ourselves is one of the first things we learn and therefore shows our dominant side earliest. No, I never had a broken arm or wrist as a child leading to a change over from the right. But I naturally played basketball and used scissors right handed. The scissors I can almost understand. Most people are forced into using right handed scissors by a lack of left-handed scissors but I was actually bought left-handed scissors and found I could not use them, much as left-handed people have difficulty using right-handed scissors. I was however, subjected to a series of obnoxious basketball coaches (even into college) who insisted that I should use my left hand as "I was naturally inclined" towards it. Thank you Coaches Kearney, Simpson, Tollet, Vining, and Davis for denegrating me and destroying my self-confidence. I was most assuredly right-footed. I could not produce a left-handed layup from the beginning nor could I train myself to get the footsteps leading to do one correctly. The fact is my left hand has always been weaker than my right. The most dextrous acts, eating and writing, are done lefty. Everything else is done as a righty. It is almost as if something forced me into being left-handed but restricted my full left-handed potential.
Reply | Report Abuse | Link to thisIn schools before the 1970's there was a movement to "correct" left-handedness. To some extent there still is today. (Just look at the questions on Yahoo and other sites about whether parents should force their children into being right-handed) I was not part of this experimentation which was later shown to increase the frequency of stuttering among naturally left-handed children due to its association with the LRRTM1 gene.
In the end, there is nothing wrong with being left-handed. In some instances it can be a boon. For those of us that use one for certain tasks and the other for different functions, leave us to our machinations.
It is very possible, but I wouldnt recommend it. It will confuse you very much, and you cant really change it, espicially now that your older. When I was in kindergarten i was forced to use my right hand an my handwriting is terrible and my both of my hands shake whenever i try to do something. So even if you are older then I was, it will still have a negative effect on you.
Reply | Report Abuse | Link to thisNooooooo defintaly not. My 1st grade teacher tried to change me to be right-handed but failed. If you change your child to be right handed they will never reach there full potential. I freak out whenever I hear someone trying to change there childs hand from lefty to righty or even the other way around. Please just don't do it. Even if you do, she'll probaly still do somethings left handed. However, even though she is left handed she'll probaly adapted to do some stuff right handed. I know its been like 4 years since you posted that but I strongly encourage you NOT to change her perfered hand to the right God mayed her left handed so let her stay that way.
Reply | Report Abuse | Link to thisNooooooo defintaly not. My 1st grade teacher tried to change me to be right-handed but failed. If you change your child to be right handed they will never reach there full potential. I freak out whenever I hear someone trying to change there childs hand from lefty to righty or even the other way around. Please just don't do it. Even if you do, she'll probaly still do somethings left handed. However, even though she is left handed she'll probaly adapted to do some stuff right handed. I know its been like 4 years since you posted that but I strongly encourage you NOT to change her perfered hand to the right God mayed her left handed so let her stay that way.
Reply | Report Abuse | Link to thisthe same thing with me however i stopped them from trying to make me right-handed the said thing is that teacher tried to change me and im only 15 years old now....
Reply | Report Abuse | Link to thisDo not force your child to be left or right. what ever comes naturally is the best option. I'm the only lefty in my immediate family. out of the 40 family members that i have I only have one cousin and uncle that are also left handed. I use everything with my left hand first, except a couple of items (Examples) a Mouse for a computer, scissors, power tools, and musical instruments like a guitar. Alot of games and sports are for right handed people, when you throw a lefty in (like boxing) it has its advantages and disadvantages. let the selection be Natural...
Reply | Report Abuse | Link to thisits hard to say, my little sister used her left hand alot when she was a baby (around 6 months) now shes 5 and fully in control of her right hand
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