Parents shape children through genes they don't pass down
Study of 30,000 families shows parental genes shape offspring traits through family environment independent of inherited DNA. Genetic imprinting—where genes behave differently based on parental origin—appears far more widespread than previously understood.
- Study analyzed 30,000 families from Norwegian and Estonian biobanks
- Indirect parental genetic effects rival direct inheritance in importance
- Genetic imprinting appears far more widespread than previously understood
- Three traits examined: height, body mass index, and academic performance
International research reveals parental DNA influences children's height, weight, and academic performance through environmental factors beyond genetic inheritance, with indirect effects comparable to direct heredity.
A child's height, weight, and school performance are shaped not only by the genes she inherits from her parents, but by something subtler and harder to measure: the world her parents' own genetics create around her. An international team of researchers has now developed a way to untangle these invisible threads, revealing that the indirect influence of parental DNA—through the environment parents construct—carries almost as much weight as the genes passed down directly.
The study, led by scientists at Austria's Institute of Science and Technology and Norway's Institute of Public Health, analyzed genetic and physical data from more than 30,000 families across two major European biobanks. The researchers examined three specific traits in children: height, body mass index, and performance on national school tests taken around age ten. What they found challenges a long-standing assumption in genetics: that a person's traits flow primarily from their own DNA. The work, published in Cell Genomics, introduces a new method capable of separating direct genetic inheritance from the indirect effects of parental genetics operating through family environment—a distinction researchers had never cleanly made before.
The mechanism at work is both straightforward and complex. Parents transmit genes, yes, but they also create a family environment shaped by their own genetic makeup. A parent predisposed to athleticism might establish a household culture around physical activity. A parent with genetic markers linked to academic aptitude might fill the home with books and conversation. These environmental pressures, rooted in parental genetics but not directly inherited, can influence how a child develops. Matthew Robinson, a professor at the Austrian institute and co-director of the study, explained that separating these indirect genetic effects from direct inheritance—and from a third phenomenon called genetic imprinting, where certain genes behave differently depending on whether they come from mother or father—had eluded researchers until now.
The team, working with postdoctoral researcher Ilse Krätschmer and Alexandra Havdahl, director of the Norwegian institute's center for genetic epidemiology and mental health, controlled for a confounding factor that had muddied previous research: assortative mating, the tendency of people with similar traits to pair together. Tall people marry tall people. This pattern, if not accounted for, can distort which effects belong to which cause. The researchers also examined genetic imprinting—the biological mechanism by which some genes switch on or off depending on their parent of origin—and found evidence suggesting it may be far more widespread in humans than previously understood.
The results show that while a child's own inherited DNA remains the primary genetic driver of the three traits studied, the combined weight of indirect parental effects and imprinting effects approaches that of direct inheritance. In other words, ignoring these indirect pathways leaves a fundamentally incomplete picture of how genes shape human characteristics. Many of the same genetic regions contributed to both direct and indirect effects, suggesting the mechanisms are deeply intertwined.
The implications ripple outward. Understanding how genetic and environmental factors interact could clarify the origins of complex diseases—metabolic disorders, mental illness, conditions involving multiple biological and environmental players. It could also point toward more precise, personalized treatments by identifying which genetic effects operate directly on an individual and which are mediated through family environment. Robinson noted that the findings underscore a central truth: the relationship between genes and traits is genuinely intricate, with serious consequences for how genetic research is interpreted. As Krätschmer put it, the method now allows researchers to determine whether a genetic effect belongs solely to one parent's DNA and not to the child's own—a distinction that could reshape how we understand inheritance itself.
Notable Quotes
The relationship between genes and traits is genuinely complex, with serious consequences for how genetic research is interpreted— Matthew Robinson, co-director of the study
Genetic imprinting could be much more widespread in humans than previously thought, which is surprising given that the underlying mechanisms are still not fully understood— Matthew Robinson
The Hearth Conversation Another angle on the story
So if a child inherits tall genes from both parents, she'll be tall. But you're saying there's something else happening too?
Yes. Her parents' height influences the family environment—maybe they play basketball together, maybe they buy clothes that fit tall frames, maybe there's a cultural expectation around physical capability. That environment, shaped by their genetics, shapes her development too. It's not in her genes, but it flows from theirs.
And this indirect effect is almost as strong as the genes she actually inherited?
The study suggests it can be. When you add up all the indirect effects—the environment, the imprinting, the parental influence—it's comparable to direct inheritance. We've been measuring only half the picture.
What's genetic imprinting? That sounds like something specific.
It is. Some genes turn on or off depending on whether they came from your mother or your father. A gene from dad might be silent; the same gene from mom might be active. The study found this happens far more often than anyone thought.
Why does that matter for medicine?
Because if you're trying to understand why someone develops a disease, or design a treatment, you need to know which genetic effects are direct and which are indirect, which come from mom and which from dad. The old model missed all of that. This method lets you see it.
So parents shape their children in ways that have nothing to do with the genes they pass down?
Exactly. And yet it's still genetic influence—just operating through a different channel. That's what makes it so hard to see, and why seeing it clearly changes everything.