New twin research shows that innate IQ plays a major role in predicting your future socio-economic status. The study, which follows twins during the crucial early adult years, reinforces the view that heredity and genes shape our life opportunities – and the people we become.
The saying “to be born with a silver spoon in one’s mouth” suggests that wealth and prosperity stem from the parents’ fortune. There is certainly some truth in that, but it is far from the whole truth.
“The so-called ‘silver spoon’ isn’t as big as you might think. Your home life also depends on your genes,” says personality psychologist Petri Kajonius, who recently published a study in Scientific Reports.
The study is based on data from the German TwinLife project, which tracks twins over time to understand how genes and environment influence life. A total of around 880 individuals were included, half of whom were identical twins and half fraternal twins.
The pairs of twins grew up in the same family and therefore shared the same upbringing. Since identical twins share all their genes and fraternal twins share only about half, the researchers were able to establish how much of the differences between individuals is due to genes, and how much is due to environment.
The participants’ IQs were tested at the age of 23, and at the age of 27 their socio-economic status – education, occupation and income – was measured. This age range was chosen to capture a period when many had established themselves in adult life and begun their careers. The results show that, statistically speaking, IQ is approximately 75 per cent genetically predicted and that the correlation between IQ and socioeconomic status are mostly explained by genetics, 69-98%.
“We knew this before, but this study shows even more clearly that we are driven by our genes and become who we are largely because of them,” says Petri Kajonius.
Does that mean that policies aimed at levelling the playing field – such as those designed to help young people from families with little tradition of higher education achieve better grades – are a waste of time? Is a person’s future still predicted by their genes?
“The study shows that we are born with different genetic predispositions and that it is difficult to bring about long-term change in this regard through policy measures.”
It might sound as though everything is predetermined.
“As a researcher, my job is to describe reality as accurately as possible. If we want to change society, we must, of course, understand the underlying assumptions.”
Furthermore, Kajonius argues, the results could also be viewed with a degree of relief. Parents can stop blaming themselves. Admittedly, targeted interventions are valuable, but in the long run, the scope for influencing one’s children’s socio-economic success is quite limited. And for young people, perhaps the findings might lead them to focus on what they enjoy most and are best at, rather than what maximises their socio-economic status.
Limitations of the study:
A limitation of this study is that it has not controlled for parents’ IQ and socio-economic status. A more general limitation of this type of model is that they often fail to account for the interaction between genes and environment – that is, genetic effects can manifest differently depending on upbringing. This means that the high figure for genetic influence (75 per cent) may partly reflect such interaction effects, possibly by up to around 15 percentage points.
Scientific Reports
Longitudinal associations betweencognitive ability and socioeconomicstatus are partially genetic innature