Children with a higher polygenic index for attention-deficit hyperactivity disorder tend to see a higher likelihood of their parents separating or divorcing, according to new research. The findings suggest that families are dynamic systems where a child’s inherited characteristics can actively shape the life trajectories of their parents. The research was published in Proceedings of the National Academy of Sciences of the United States of America.
Family research often focuses on how parents shape their children. A 2017 study demonstrated that parents’ genetic traits indirectly shape the home environment they create for their children. This progression in the literature has led scientists to ask whether the influence might operate in the opposite direction.
A polygenic index is a statistical construct scientists use to estimate the likelihood of a specific trait or condition. It is calculated by adding up the effects of many small genetic variations across a person’s DNA, weighted by how strongly they associate with a trait in large population samples. Rather than measuring an internal biological mechanism or an absolute predisposition waiting to be realized, a polygenic index is a risk estimate that depends heavily on the specific population and environment it was derived from. Evocative gene-environment correlation is the related concept that a person’s genetically influenced tendencies can provoke specific reactions from the people around them.
Researchers have started applying this concept to family dynamics. A 2024 study of adoptees indicated that children’s inherited traits can actively shape how warmly their parents treat them, providing evidence that children influence their own caregiving environment. This builds on research covered by PsyPost in early 2025, which found that early childhood traits related to attention and hyperactivity can alter family dynamics by increasing the likelihood of experiencing childhood maltreatment.
Attention-deficit hyperactivity disorder, or ADHD, is a neurodevelopmental condition characterized by patterns of inattention, hyperactivity, and impulsivity. To understand how children might shape broader family structures, a research team led by Evelina T. Akimova at Purdue University and Torkild Hovde Lyngstad at the University of Oslo examined whether children’s polygenic indices predict major parental decisions. They set out to determine if a child’s statistical genetic risk estimates were associated with parental outcomes like having another baby, getting married, or ending a relationship.
The researchers analyzed data from the Norwegian Mother, Father and Child Cohort Study. They looked at genetic and administrative data from 40,000 genotyped family trios, consisting of a mother, a father, and a child. The data included genetic information derived from blood samples taken during pregnancy and at birth.
The team tracked family demographic changes through Norwegian administrative registers, which provided objective records of marriage, separation, and childbirth. By comparing the child’s polygenic indices for various physical and mental health traits against these family outcomes, the researchers could look for patterns. Importantly, they controlled for the polygenic indices of both parents, allowing them to isolate the specific influence of the child’s genetic associations on the family environment.
The researchers found that for most behavioral and physical health traits, the child’s genetic profile had no statistically significant impact on family demographic events. Traits like asthma, body mass index, and cognitive performance did not reliably predict whether parents would have another child, marry, or separate. The notable exception was the polygenic index for ADHD.
An increase in a child’s polygenic index for ADHD was reliably associated with an increased risk of parental partnership dissolution. Specifically, a one standard deviation increase in the child’s ADHD polygenic index predicted a 7 percent relative increase in the odds that their parents would separate or divorce. When the researchers broke the data down further, they found that this effect was highly specific to certain types of families.
The association between a child’s ADHD genetic index and parental separation was driven primarily by families with daughters. For girls, a one standard deviation increase in the ADHD polygenic index was associated with an 11 percent increase in the odds of parental dissolution. For boys, the increase was less than 4 percent, and the result was not statistically significant. The authors propose that because ADHD in girls often presents as issues with attention and emotion regulation rather than overt hyperactivity, it may be underdiagnosed, leading to unaddressed behavioral challenges that strain family relationships.
Socioeconomic status also played a moderating role. In families with above-average educational attainment, a one standard deviation increase in the child’s ADHD polygenic index was associated with a 15 percent increase in the odds of partnership dissolution. In families with below-average socioeconomic status, the effect was not statistically significant. The researchers suggest that behavioral difficulties might conflict more intensely with the rigid academic and developmental expectations often present in higher-status households.
Maternal age at the time of the first birth also altered the outcomes. In families where the mother was older than the median age at her first birth, an increase in the child’s ADHD genetic index predicted a 10 percent increase in the odds of parental separation. In these same older-mother families, the researchers also noted a separate effect regarding anxiety. A higher polygenic index for anxiety in the child was associated with a 10 percent increase in the odds that the parents would marry after the child’s birth, suggesting that older parents might respond to an anxious child with stabilizing commitments.
As with all research, there are some caveats to consider. The study is based entirely on data from Norway, a country with a universal welfare state, high levels of gender equality, and robust family support systems. The ways in which child traits evoke parental responses might look different in countries with less institutional support or different cultural norms regarding marriage and divorce.
There are a few other things to keep in mind regarding the data. The Norwegian cohort study relied on voluntary participation, which resulted in a sample that slightly overrepresents families with higher socioeconomic status. Families experiencing multiple extreme adversities are likely underrepresented, which could affect the prevalence estimates of certain family events.
The genetic measures themselves also have limits. Because polygenic indices are statistical models rather than direct biological pathways, their predictive accuracy heavily depends on the reference populations used to create them. The polygenic indices used in this study were derived from genetic studies of populations with European ancestry, meaning the findings may not generalize to people of other ancestral backgrounds. Additionally, current polygenic indices only capture a small fraction of the total genetic influence on a complex condition like ADHD.
The study, “When children shape their families: Evocative effects analysis of 40,000 trios from the Norwegian Mother-Father-and-Child Study,” was authored by Evelina T. Akimova, Agnes Fauske, Ruth Eva Jørgensen, Alexandra Havdahl, Elizabeth C. Corfield, Melinda C. Mills, and Torkild Hovde Lyngstad.