Sees all out behaviour is rooted for our biological structure and that everything psychological has a biological basis
1) genes- specific genes and combinations of genes will have an influence on both the physical and psychological aspects of people. Genes that code for characteristics or behaviours that are beneficial to survival will be passed on to the next generation
2) The biological structure-the behaviour of the individual is controlled and coordinated by the brain and the nervous system
3) The chemistry of the body-hormones in the body and neurotransmitters in the brain have a much impact on our behaviour