The nature of nurture was a landmark finding in behavioural genetics. There is robust evidence to support that factors previously considered purely ‘environmental’, and therefore any correlated psychological traits partially attributed to such factors, are themselves heavily influenced by our DNA.

Something as seemingly random as total hours spent watching TV is highly heritable. Along with this are even more curious heritable’ environmental’ factors such as the magnitude and number of extreme life events (divorce, job loss, illness), quality of friends, the amount of time a parent reads to their child, and even the climate in which a person lives.