A follow-up study of twins in Germany undermines the concept that the home environment and schooling are important for personal development.
A large-scale study conducted in Germany with over 800 pairs of twins found that heredity is the major cause of IQ disparities among young people.
According to a study published in the journal Scientific Reports, genetic inheritance accounts for three out of four variances in IQ, which also has a major impact on school performance, job choice, and income.
The findings call into question the concept that the home environment and economic resources available throughout childhood are the most important factors influencing social achievement.
According to research led by psychologist Petri Kajonius, genetic variables account for 69% to 98% of the relationship between IQ and socioeconomic level.
A twin experiment demonstrates the power of genetics
The TwinLife project tracked 880 young twins in Germany, both identical and fraternal, and was analysed by researchers from Lund University. This technique enabled researchers to examine siblings raised in the same familial setting but with distinct genetic makeups.
The researchers tested the subjects’ IQ at age 23 and then assessed their socioeconomic situation four years later using markers such as education level, occupation, and income.
The results revealed that 75% of the differences in intelligence among participants are due to genetic factors. The influence of heredity is also reflected in the relationship between intelligence and socioeconomic status, determined by genetics in 69% to 98% of cases.
The impact of the environment, family resources, and other circumstances explains a smaller proportion of these differences.
The study challenges the widespread belief that family background and wealth are the main drivers of personal success. “The so-called ‘silver spoon’ isn’t as big as people think. Life at home also depends on genes ,” Kajonius argued.
While social origin has some influence, the research indicates that genetic inheritance weighs much more heavily in accessing educational and employment opportunities.
According to data research, genetics accounts for between 49% and 66% of the variations in educational achievement and 32% to 71% of the variances in occupational level. This effect outweighs that of contextual elements, including school, friends, and family cultural capital.
Social policy and the scope of action
The Lund University team’s results raise doubts about the genuine reach of governmental measures aimed at equalising opportunity. Kajonius said that “the study shows that we are born with different genetic predispositions and that it is difficult to generate lasting change through policy measures”.
According to the research, while interventions can give immediate chances, parents, schools, and governments have less power to change individual fates than imagined.
The psychologist argued that “psychology manifests itself in life primarily through genetic makeup, not so much through environmental conditions”. He claims that this may explain why many social equality measures have minimal long-term impact.
Limitations of the model: genetics are not destiny
The report admits certain serious limitations. IQ and parental socioeconomic position were not included, and any potential complicated interactions between genetic and environmental variables were removed from the analysis.
Furthermore, the four-year follow-up time may be insufficient to track the participants’ overall professional progress.
The authors emphasise that genetics do not decide a person’s fate, but rather raise certain odds. “Heritability does not imply determinism, only increased probabilities,” Kajonius said.
For example, they discuss myopia, which is a hereditary propensity that may be corrected for with suitable measures such as wearing spectacles.
Experts believe that knowing genetic variation might help create more successful public policies that focus on developing individual skills rather than achieving the same objectives for everyone.
Genetics defines the range of possibilities, and personal work decides where each person falls within that range.
The study adds to the data on the impact of biology on intellect and social achievement while leaving open the question of how to balance the importance of genetic inheritance with the significance of chances and human effort.
