A good article appeared in Time (Canadian edition) on June 2, 200: What make you who you are. Matt Ridley writes that the old nature-nurture debate is moot because genes and environment are not the opposite of one another; they may essentially be the same thing. Genes predispose us to respond to the environment in certain ways. But our responses (ie, our behaviour) can change our genes by turning them on and off. Genes set up the body as well as the opportunity for the environment and experience to completely dismantle what they set up in the first place. Here are some good excerpts from the article (his writing is far better than any of my paraphrasing):

"To appreciate [this new paradigm that sees the nature-nurture debate as dead], you will have to abandon cherished notions and open your mind. You will have to enter a world in which your genes are not puppet masters pulling the strings of your behavior but puppets at the mercy of your behavior, in which instinct is not the opposite of learning, environmental influences are often less reversible than genetic ones, and nature is designed for nurture" (p. 36).

"What we inherit is not a fear of snakes but a predisposition to learn a fear of snakes—a nature for a certain kind of nurture" (p. 36).

"Genes are not puppet masters or blueprints, nor are they just the carriers of heredity. They are active during life; they switch one another on and off; they respond to the environment. They may direct the construction of the body and brain in the womb, but then almost at once, in response to experience, they set about dismantling and rebuilding what they have made. They are both the cause and the consequence of our actions" (p. 39).