ABSTRACT
This chapter explains that genes and the environment play a significant role in human development. A baby is born with a certain set of predispositions that, given certain environmental conditions, will lead to the development of behaviours or attributes later in life. There are many different ways that genes can exert and influence on the developing child. The product of a single fertilized egg and two eggs, each are fertilized by a separate sperm. The concordances between monozygotic and dizygotic twins can get an estimate of heritability. The existence of monozygotic and dizygotic twins has allowed scientists in a field called behavioural genetics to do some important research on the heritability of certain traits. Most personality traits have heritability's of 50" and the variation among people is due to genes. The chapter concludes that environmental riskiness can have effects on the reproductive development of humans and other animals.
