One pig savors a ripe banana, whereas its cloned sister turns up its snout. Another always thrashes its trotters to get away when it is picked up, whereas the others nuzzle into a human embrace. Although clones have been described as identical twins, studies of the behavioral--and even physical--traits of cloned animals are showing that that is not necessarily the case.

Ted Friend and Greg Archer of Texas A&M University created the cloned piglets. They observed as much physical and behavioral variation among the members of two litters of cloned pigs (of four and five individuals, respectively) as among those of two litters of eight pigs bred naturally. Not only did the cloned siblings show distinct food preferences and temperaments, but they also varied in physical characteristics: some had more bristly coats or fewer teeth than others did.

This article was originally published with the title Ma's Eyes, Not Her Ways.

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