Your Parents’ DNA May Shape Your Traits in Ways You Didn’t Directly Inherit
Genes don’t tell the whole story of why traits run in families. A new study of roughly 30,000 families found that a parent’s DNA may shape children’s height, body weight, and school performance not only through the genes passed down at conception, but through the environment those genes help create. Moreover, which parent a gene comes from can change what it actually does in the child who inherits it.
Published in Cell Genomics, the research found both of these forces are substantially larger than standard genetic studies have been capturing. Together, they rival the direct effect of a child’s own inherited DNA, a finding that points to a significant blind spot in how scientists have been reading the genome.
Parental DNA Linked to Children’s Height, Weight, and School Scores
To understand why this matters, consider what genes actually do inside a family. A child inherits one copy of each gene from mom and one from dad. Standard genetics says those inherited copies drive the child’s biology. But families do not operate in a vacuum. Parents act on their own genetic tendencies every day, and those actions may shape the world their children grow up in.
Until now, measuring those overlapping influences was extremely difficult. The new study introduced JODIE, a statistical tool designed to separate three distinct genetic forces at once: the effect of a child’s own inherited DNA, the effect of the mother’s genes on the child’s environment, and the effect of the father’s genes on the child’s environment. It also tracked a fourth force, parent-of-origin effects, tied to a process in which one parent’s copy of a gene is switched on while the other parent’s copy stays silent.
Previous methods had struggled with a particular wrinkle: people tend to have children with partners who are genetically similar to them. That pattern creates statistical echoes that can make a child’s own DNA look more influential than it really is, while obscuring the parent-of-origin contribution. JODIE was built to correct for this.
Data came from the Norwegian Mother, Father, and Child Cohort and the Estonian Biobank, covering three traits: height, body weight relative to height, and childhood educational test scores. Educational scores were measured around age 10 in the Norwegian children; height and body weight measures from Norway came from children ages 7 to 8, while Estonian data covered adults.
Mom’s and Dad’s Genes Each Contribute Roughly Equally to Indirect Effects
A child’s own inherited DNA remained the strongest single driver of all three traits. But when the indirect effects from both parents are combined with the parent-of-origin effects, their total is comparable to the direct effects, too large to treat as background noise.
For height and educational scores, the genome regions where a child’s own genes act tend to overlap with the regions where parental genes exert their environmental influence. Maternal and paternal contributions were roughly equal in size.
Researchers identified specific locations across the genome tied to each trait: 276 linked to height, 15 to body weight, and 11 to childhood test scores. Most held up when checked against independent data from the UK Biobank and the Generation Scotland study. Notably, these locations were spread across the genome rather than concentrated in regions already known for parent-of-origin switching, pointing to a broader role for this phenomenon than previously understood.
A few locations stood out. One near a gene involved in brain and facial development was linked to childhood educational scores. Another, inside a gene active in sperm-producing cells, was associated with height, a detail the researchers flagged as potentially relevant to how fathers pass chemical markers alongside their DNA. A third, near a gene showing activity in testis tissue, was connected to body weight.
Why Standard Genetic Studies May Miss Part of the Picture
In the study’s simulations, several commonly used approaches became biased under the more complex family scenarios JODIE was designed to handle. They overestimated how much a child’s own DNA was responsible for a given trait while underestimating the parent-of-origin contribution. A common shortcut of estimating missing parental DNA rather than collecting it directly also systematically underestimated indirect parental effects.
Source : https://studyfinds.com/parental-dna-shapes-children-unexpected-ways/