Nature versus nurture? It's a debate that's been raging for centuries. The overwhelming consensus right now is that it is not one or the other but rather a complicated mixture of the two. Essentially, it's a draw.
This is a conclusion that appears to be backed up once again by a meta-analysis of five cohort studies published in the Proceedings of the National Academy of Sciences examining the effect genes have on social mobility. The result: How successful you are is not predetermined at birth, but certain markers in your DNA can help predict how well you do educationally and professionally, at least to a point.
Or, as Daniel W. Belsky, lead author and assistant professor in the Department of Population Health Sciences at Duke University, told Harvard Business Review in 2017 following the publication of one study involved in this meta-analysis, "Though DNA isn’t destiny, it does have something to say about the kind of people we become and what we achieve."
Adding, "we also know that human development stems from a complex interaction of the genes we inherit and the environments we encounter. Nature and nurture combine to make us who we are. We’re just beginning to understand how that interplay operates."
It is no secret that a person's success and wealth are heavily influenced by their family background. In 2014, a study based in the UK found the association between inheritance and social standing is stronger than it is for height.
But do we inherit genetic (dis)advantages or social (dis)advantages? Genetic advantages are encoded in our DNA. Social advantages are passed on and may include education, inherited wealth, contacts, and even helpful behaviors, such as a hardworking attitude.
To find out, Belsky and his team focused on five longitudinal studies examining social mobility. A positive correlation between education-linked genetics and upwards social mobility, the theory goes, would suggest genes influence success, at least to some extent.
The studies – one from New Zealand, three from the US, and one from the UK – took place between 1957 and 2013 and involved over 20,000 individuals across different generations. To measure social mobility, researchers used various educational, economic, and occupational standards including GCSE results, education status, occupational income, and professional status.
Despite covering different countries and age groups, all five showed a positive correlation between people with "educational-linked" genetics (referred to as a "polygenic score") and social mobility. This occurred regardless of socioeconomic class and, in some cases, even family. When comparing brothers and sisters, for example, the researchers noticed the sibling with the higher polygenic score tended to be more successful.
Interestingly, a child's mother's genetics were even more telling of the child's later success than their own genes, suggesting upbringing plays a crucial role.
To sum it up in the authors' own words, polygenic scores can “modestly predict a person’s educational and economic success”. However, it's worth pointing out that it accounts for just a few percentage points in variations between people. So a low polygenic score does not doom you to failure.
"We’re talking about average outcomes," Belsky added.
"Some people with low polygenic scores went on to have very successful lives, and some with high scores did not. There are many other nongenetic tests you can administer to children and adults that will give you a much better read on their ability to achieve than we can get out of the genome."