Published: 23-04-2026 00:30 | Updated: 23-04-2026 00:30

Family environment shapes life outcomes across generations

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Adopted children who have grown up in more favourable family environments than their siblings are at lower risk of mental health issues, criminality and social problems – benefits that, in some cases, extend to the next generation. These are the findings of a new study of Swedish siblings published in The BMJ.

Erik Pettersson. Photo: Gunilla Sonnebring

To determine the extent to which these factors can be influenced, researchers at Karolinska Institutet studied pairs of siblings in Sweden where one sibling was adopted away from a high-risk family while the other remained with and grew up with their biological parents. This allowed them to compare the long-term effects of different family environments while taking genetic factors into account.

“Our study shows that a more favourable home environment can make a big difference, particularly for children who start life with clear risk factors,” says Erik Pettersson, associate professor at the Department of Medical Epidemiology and Biostatistics at Karolinska Institutet.

Followed over 12,000 siblings

The study is based on Swedish population registers and covers just over 12,000 full and half-siblings born between 1950 and 1980. All come from families where at least one parent had experienced some form of psychiatric or social issue, such as mental illness, criminality or attempted suicide, and where at least one child had been given up for adoption before the age of ten. Families who took in adopted children often had greater resources and higher socio-economic status.

The results show that the adopted children had a lower risk of mental illness, criminality and dependence on social security benefits as adults, compared to their siblings who grew up with their biological parents. They also performed better at school and, on average, attained a higher level of education. Furthermore, men who had been adopted performed better during military conscription, both on intelligence tests and in interviews measuring stress resilience and social adaptability.

May affect the next generation

The researchers also investigated whether these differences were passed on to the next generation. In total, nearly 22,000 children of the sibling pairs were studied.

On average, the children of adopted siblings displayed higher functioning than their cousins, for example a lower risk of criminality and financial problems. The effects were weaker than in the previous generation, but pointed in the same direction.

“This suggests that improved living conditions benefit not only the individual, but also the next generation,” says Erik Pettersson.

Value of support measures

He emphasises that the results should not be seen as an argument for adoption, which is currently uncommon in Sweden. However, he believes the study highlights the value of interventions for children in vulnerable environments.

“Research into the effects of various support measures aimed at giving children a better upbringing is both limited and fragmented,” he says. “Some studies show significant long-term benefits; others show little or none at all. Our study suggests that the potential is considerable, even though we cannot say which measures are most important.”

The study was funded by the Swedish Research Council, the Swedish Research Council for Health, Working Life and Welfare, the Swedish Society of Medicine, the Söderström Königska Sjukhemmet Foundation and the Swedish Brain Foundation. See the publication for information on potential conflicts of interest.