Here’s a fascinating little tidbit from Book Chat at the New York Times. Jane Waldfogel is the author of a book called “Britain’s War on Poverty” as well as other books. She’s interviewed here about the relative importance of genetics vs. parenting in outcomes for children. It’s worth your time to read.
One of the things she discusses is studies of identical twins adopted out at birth. These are often cited because they seem to provide a nice test for the DNA-controls thesis as identical twins adopted into different households have identical DNA though they grow up in different environments. (At least some do show strong similarities in the outcomes for the separated twins.) Her critique of these studies is really thought-provoking.
I have to say that it seems fairly obvious to me that the answer to the nature/nurture question must be both, but it’s equally obvious that this result does not satisfy everyone.