Perhaps the original question was too broad. The more I think about this issue, the more convinced I am that the question of nature vs. nurture has to be answered on a case by case basis. For instance, I've read that twin studies indicate intelligence is 80% nature (genetic) and only 20% nurture (environment), while diabetes is about 50% nature and 50% nurture. So, it varies depending on specifically what thing one is talking about.