Our parents’ genes have an important influence on our lives – even those that we did not inherit from them: through their impact on our home environment, they influence, among other things, our body weight and our school performance. In genetic analyses, it has so far been difficult to distinguish between direct and indirect influences. A new method now makes it possible to more clearly separate the contributions of the child’s genes and the genetic fingerprint of its environment. The results illustrate the complex interaction between inherited and non-inherited genes.
When two people have a child together, they each pass on half of their set of chromosomes to the offspring. The combination of maternal and paternal genes determines basic characteristics such as our eye color, our blood type, our susceptibility to certain diseases and many other characteristics. In some cases, the same gene has different effects depending on which parent it comes from. This so-called parent-of-origin effect uses epigenetic patterns to ensure that for certain genes only the maternal or paternal copy is activated. In addition, even genes that we did not inherit can influence us. The genes of our parents also determine how they behave and how we are raised.
Direct and indirect influences
“Indirect genetic effects and parent-of-origin effects are different phenomena that can explain how genes shape traits beyond the standard model of a person’s direct DNA influence,” explains Matthew Robinson from the Institute of Science and Technology Austria (ISTA). “However, it has not yet been possible to quantify these two mechanisms separately and at the same time show their interaction.” Together with a team led by first author Ilse Krätschmer, Robinson has developed a method to separate the different influences from each other.
For their study, the researchers analyzed genetic data from more than 30,000 mother-father-child trios from a large Norwegian cohort. They looked at the children’s height, body mass index and performance on national school tests around the age of ten and related these values to the DNA of the children and their parents. They also compared the results with the data from around 10,000 other families from the Estonian Biobank (EstBB).
Complex relationships
The result: “We found that direct effects of one’s own genes make the largest contribution to trait variation, but the combined indirect parental and parent-of-origin effects are similarly significant when taken together,” reports the research team. In particular, parental effects had a greater influence on school success and body weight. “Our results highlight that the relationship between genes and traits is really complex – and that has important consequences for how we interpret genetic research,” says Robinson.
Further genome-wide association studies also showed that the direct and indirect effects were mediated by similar DNA regions. “This suggests that the same loci shape a child’s characteristics in two ways: both through the genes that the child carries and through the environment that the parents create,” explains Krätschmer. According to the research team, the approach can also be extended to other characteristics and could, among other things, help to better understand the genetic basis of metabolic diseases or psychological disorders. “Ultimately, our method allows us to determine whether a genetic effect is only related to the DNA of a parent and not to the child’s own DNA,” says Krätschmer.
Source: Ilse Krätschmer (Institute of Science and Technology Austria, ISTA, Klosterneuburg, Austria) et al., Cell Genomics, doi: 10.1016/j.xgen.2026.101277