This study finds that genetic inheritance has more influence than the shared social environment alone in perpetuating social inequalities. However, the importance of genes varies according family environment: genetic influences are stronger among those growing up in the most advantaged families.
The researchers studied 6,500 pairs of twins born in Finland between 1975 and 1986. They used administrative registers to identify the twins and did not know which were identical, so they compared single-sex pairs of twins with mixed-sex pairs, looking at their levels of education, socio-economic status and income at around the age of 30.
The results suggest the influence of siblings’ shared environment, independently of the genetic influences, on their later outcomes is negligible. By contrast, genetics play a significant role, but also depending on the social environment, particularly in higher social groups and particularly if parents’ social status is observed later rather than earlier in childhood – this suggests it is parents’ potential to social achievement, rather than their actual status, that matters most.
The research also finds strongest genetic influences are linked to educational and occupational status. Genes have considerably less impact on children’s future income than on their education or occupation.
This is significant, the researchers say, because it suggests that the success or failure in education cannot explain much of what happens to children by the time they are in their thirties.
The results underline the importance of understanding the interplay between genetics and environment. Genetic inheritance plays a key role and should be a major strand in research on intergenerational social mobility.