"Nature, nurture, or a combination of the two" is a gross mischaracterization. You have been given specific risk factors, of course you have to explore the spec

"Nature, nurture, or a combination of the two" is a gross mischaracterization. You have been given specific risk factors, of course you have to explore the specific mechanisms, but you have got a starting point. It is like saying that because some smokers don't get chronic respiratory disease, all observations of correlation are meaningless until someone proves the exact biochemical effects that link tobaco with such diseases.