The heritability of behavior. Why do we act the way we do? The common belief tends to points towards our experiences in life being what eventually determine our very own approach to it. But, such an explanation may be overlooking a fundamental part of what makes us who we are: our genome. In this extract from the book "Genetic Twists of Fate", professors Stanley Fields and Mark Johnston study in more depth new research suggesting our reactions and characters are not only determined by our nurture, but also our nature.