The uterine environment is key to a fetus' development. The increasing popularity of in vitro fertilization (IVF) provides an opportunity to tease out environmental effects from genetic effects in humans by allowing the comparison of outcomes in babies born to related and to unrelated mothers. Analyzing children born through IVF, Frances Rice et al. were able to separate the effects of genes and prenatal environment related to a fetus' prenatal exposure to smoking, which has been linked to low birth weight and antisocial behavior. The authors analyzed 779 children born via IVF to related and to unrelated mothers and found that low birth weight occurred when mothers smoked regardless of their relatedness to the fetus, but antisocial behavior was associated with maternal smoking only when children were born to related mothers. This method may allow researchers to differentiate the effects of genes and environment on a variety of other conditions, the authors say.
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