The three laws of behavioral genetics may be the most important discoveries in the history of psychology. Yet most psychologists have not come to grips with them, and most intellectuals do not understand them …. Here are the three laws:
The First Law. All human behavioral traits are heritable.
The Second Law. The effect of being raised in the same family is smaller than the effect of genes.
The Third Law. A substantial portion of the variation in complex human behavioral traits is not accounted for by the effects of genes or families.

The First Law. All human behavioral traits are heritable. - The Blank Slate (2002)