In the past decade, the Dunedin Study has taken the lead internationally in modelling how nature (our genes) interacts with nurture (our life experiences) to help predict why people behave the way they do. For example, we have shown that among children who were maltreated, those that go on to repeat the cycle of violence have a specific form of the MAOA gene, whereas those with a different form of this gene appeared resilient to maltreatment. We have also shown that the likelihood of developing psychosis in adulthood after exposure to cannabis use in adolescence is conditional, that is, it depends upon the presence of a particular ‘vulnerability’ genotype. In perhaps the best known of these nature–nurture interplay studies, we showed why certain people succumb to depression in the face of life stress, whereas others do not. This finding, along with several others, was voted to be the second most important scientific breakthrough in the world—in any branch of science—in 2003.
