The Biological Approach: the Influence of Genes, Biological Structures and Neurochemistry on Behaviour. Genotype and Phenotype, Genetic Basis of Behaviour, Evolution and Behaviour

Each individual is born with 23 chromosomes which they’ve inherited from both of their birth parents. There is a suggestion that behavioural characteristics, such as intelligence and mental illness, are inherited in exactly the same way our physical characteristics, such as eye colour and height, are. Twin studies are used to determine the likelihood that certain traits have a genetic basis by comparing concordance rates (the extent to which 2 people share the same characteristic). If monozygotic (identical) twins have a higher concordance rate than dizygotic (non-identical) twins it would suggest a genetic basis because monozygotic twins share 100% of their DNA, and dizygotic only around 50%.