The nature side of the debate cannot be a full explanation of human behaviour; this is because if genes were 100% the sole cause of a behaviour, MZ twins who share 100% of their genes should have 100% concordance rates. However, this is not the case for example in the biological explanation of schizophrenia concordance rates for MZ twins are only 48%. Therefore, there must be other factors that affect human behaviour such as the environment e.g family dysfunction (nurure). Meaning it is important to consider both influences when explaining human behaviour.
