A major study on twins is shedding new light on the long-standing debate over nature vs. nurture, suggesting that genetics may play a much bigger role in future success than many realize.
Researchers found that IQ measured at age 23 was strongly associated with socioeconomic status by age 27, including education, occupation, and income. Research suggests that much of this relationship has to do with genetics, not just upbringing.
The findings come from Germany’s TwinLife project, a long-term research effort aimed at investigating how genes and environment shape people’s lives over time.
Twin study investigating IQ and life outcomes
The study followed approximately 880 people, including both identical and fraternal twins. Roughly half of the participants were identical twins who shared all of their genes, and the rest were fraternal twins who shared about half of their genes.
Because the twins were raised in the same household, the researchers were able to compare how much of the differences between the twins were due to genetic and environmental factors.
Participants took an IQ test when they were 23 years old. Four years later, researchers assessed their socio-economic status by looking at factors such as education level, occupation, and income.
The results were amazing. The researchers estimated that IQ is about 75% genetically predicted. They also found that the association between IQ and socioeconomic status was primarily explained by genetics, with a range of 69% to 98%.
“We’ve known this for a long time, but this study shows even more clearly that we are driven by our genes and that we are primarily the people we are because of them,” says personality psychologist Petri Kajonius. scientific report.
Rethinking the “silver spoon” idea
The findings challenge the popular idea that success comes primarily from growing up in a wealthy or well-educated family.
“The so-called ‘silver spoon’ is not as big as you think. Family life is also determined by genes,” Kajonias explains.
This does not mean that the family environment has no influence. Rather, this study suggests that genetic traits can shape people’s responses to opportunity, education, and life experiences.
This research also raises difficult questions about social mobility and public policy. If genetics strongly influence life outcomes, how much can educational programs and social interventions actually change a person’s long-term trajectory?
“This study shows that we are born with different genetic predispositions, and that policy actions will be difficult to make long-term changes in this regard.”
What the findings mean for parents and young people
Kajonius says the results may actually provide some reassurance to parents.
Many parents worry that mistakes in parenting can permanently impact their future success. But our findings suggest that parents may have less control over long-term socio-economic outcomes than is commonly thought.
This does not mean that child care and educational support are not important. Targeted interventions can still help people succeed. However, research suggests that there may be a limit to the amount that external factors can reshape deeply ingrained traits over time.
For young people, the findings may encourage a different perspective on career choice and achievement.
Kajonius suggests that people may benefit more by pursuing what they naturally enjoy and are good at, rather than focusing solely on maximizing status or income.
Important limitations of the study
The researchers point out some important caveats.
One limitation is that this study did not directly control for parental IQ or socioeconomic status. Another problem is that in such studies, it can be difficult to completely separate genetics and environment because they often interact in complex ways.
For example, genetic traits may be expressed differently depending on a person’s upbringing and life environment. The researchers say this interaction could partially inflate the estimated genetic influence on IQ, potentially increasing it by as much as 15 percentage points.
Despite these limitations, this study adds to the growing body of evidence that genetics plays a powerful role in shaping intelligence, opportunity, and life outcomes.
