Any parent with more than one child can feel like a lab scientist, unraveling the questions of nature vs. nurture. On the one hand, it is jarring to realize how different two siblings can be from each other — an affirmation of the fact that they are who they are almost from the moment they are born. On the other hand we spent nearly two decades aware that we are shaping who they become, wondering (worrying) if we are doing it right or screwing it up.
Three studies out recently serve to clarify, and complicate, the nature/nurture debate.
The first, out of Cardiff University, in Wales, studied smoking during pregnancy and its relation to “anti-social behavior” (defined as bullying, throwing tantrums and disobedience) in children. Published in the February issue of the Proceedings of the National Academies of Sciences of the United States, it was a study with a twist — 533 of the children were genetically related to the mother who carried them and 195 were conceived with egg donations, meaning they did not share genes with the mother who gave birth to them and raised them.
Smoking was directly correlated with lower birth weight in both sets of children. However, while anti-social behavior was found to be higher in the biological children of mothers who smoked, it was not higher in the children who had no genetic relationship to their mothers. In other words, low birth weight is tied to environmental factors, in this case smoking, while behavioral problems are more likely genetic. (This is all seems to based on the assumption that a mother who continues to smoke during pregnancy is displaying a tendency toward anti-social behavior herself.) READ MORE