The thing that amazes me is that scientists can find fat genes/hormones in mice and humans. Tis only issues like sexuality that they cannot reproduce in lab animals. No matter which side you look at it from this means homosexuality and other behavioral issues are only found in humans ie it is learned behavior. When did you last see an animal deciding to sit on the couch and eat donuts then when he is too fat, decides to go to the gym or on Atkins? He will find a forum like this that tells him about Atkins being a fad diet and then decides etc etc The important thing is the decision making process.