4. Nature, Nurture, and Evolution

People have a deep intuition about what has been called the “nature–nurture question.” Some aspects of our behaviour feel as though they originate in our genetic makeup, while others feel like the result of our upbringing or our own hard work. In the end, however, it is an oversimplification to ask how “genetic” some particular behaviour is. Genes and environments always combine to produce behaviour, and the real science is in the discovery of how they combine for a given behaviour. This chapter is divided into two sections. First, we will go over the basics of human genetics. This is followed by a discussion of evolutionary theories of psychology.