Human interest in and concern about inheritance is very far from new. It is reasonable to assume that ideas about physical resemblances and behavioural characteristics running in families are as old as concepts of family and kinship. We can be rather more certain that from the dawn of agriculture selective breeding has been used to change the characteristics of plant crops and domesticated animals. Indeed, selective breeding may well be viewed as the first step required to create agriculture. However, a knowledge of genetics is not required to apply selective breeding to animals or plants (or humans). All that is needed is the assumption that parental characteristics are likely to be passed to offspring. Then one can breed from superior stock, or those which have desired characteristics, and avoid breeding from inferior stock.