John Hewitt is a neuroscientist who studies the biology of intelligence. He's also a parent. Over the years, Hewitt has periodically drawn upon his scientific knowledge in making parenting decisions.
"I'm a father of four children myself and I never worried too much about the environments that I was providing for my children because I thought, well, it would all work out in the end anyway — aren't the genes especially powerful?" Hewitt says.
Pregnant women hear a lot about things they should avoid: alcohol, tobacco, chemical exposures, stress. All of those have the potential to affect a developing fetus. And now scientists are beginning to understand why.
One important factor, they say, is something called epigenetics, which involves the mechanisms that turn individual genes on and off in a cell.