The secret life of twins.

This episode features a US study on the ageing process in identical twins; it supports the idea that our genes influence the way we age. Other characteristics examined in the attempt to decide whether genes or environment have the most influence are fears, attractions, intelligence and personality. Twins take part in a Maudsley Hospital research project into mental illness; one twin is schizophrenic and one is normal. Comparison of their brains may show whether a particular area of the brain is involved in this illness. Twins are also of interest to those studying the genetics of criminality. Prof. Robert Winston concludes that while we can inherit tendencies we are shaped by the environment in which we are brought up.