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Cambridge, UK – May 18, 2025 – A major new study has revealed that both genetic ancestry and parental smoking are linked to subtle increases in the number of new genetic changes, known as de novo mutations (DNMs), passed from parents to their children. The research, published in Nature Communications, was conducted by scientists from the Wellcome Sanger Institute, the University of Cambridge, and collaborators, and analyzed whole-genome data from 10,000 parent-child trios.
Unraveling the Origins of Genetic Variation
Germ cells-eggs and sperm-are responsible for transmitting genetic information to the next generation. While most changes in DNA are harmless, some can lead to serious genetic disorders. Scientists have long known that parental age, especially the father’s, is a significant factor: each additional year of paternal age results in about 1.5 more DNMs, while each year of maternal age adds about 0.4.
However, the new study goes further, examining the influence of ancestry, common genetic variants, and environmental factors such as smoking on DNM rates. By comparing the genomes of children with those of their parents, the team catalogued nearly 690,000 new mutations.
Small but Significant Ancestry Differences
The researchers found that children of African ancestry had, on average, about 67 new DNMs per generation, compared to about 64 in European, American, and South Asian groups. While this difference is modest-equivalent to having a father who is two years older-it suggests that ancestry, possibly through genetic or environmental factors, plays a role in mutation rates.
Parental Smoking: A Subtle Effect
The study also identified a link between parental smoking and higher DNM rates in children. Children with at least one parent who smoked had a roughly 2% increase in new mutations-less than one extra mutation per smoking parent over their reproductive lifespan, a similar effect to a one-year increase in paternal age.
Importantly, the researchers caution that it is too early to say whether smoking directly causes these mutations, as other environmental mutagens could be involved.
Implications for Genetics and Public Health
These findings could have important implications for future studies in population genetics and the search for genes involved in rare disorders. Current genetic models often assume uniform mutation rates across populations; the new research suggests that accounting for ancestry and environmental exposures could refine these models.
Dr. Aylwyn Scally, co-senior author at the University of Cambridge, commented, “The takeaway is that rates of de novo mutation are mostly driven by parental age, but ancestry and environmental factors such as smoking may make a small imprint.”
Dr. Hilary Martin, co-senior author at the Wellcome Sanger Institute, added, “These effects are small, but nonetheless these findings increase our understanding of factors associated with this fundamental biological process.”
Looking Ahead
The researchers emphasize that larger studies with more detailed data on environmental exposures are needed to fully understand the factors influencing mutation rates in humans.
Disclaimer:
This article is for informational purposes only and summarizes findings from a recent scientific study. The research discussed does not establish direct causation between parental smoking and genetic mutations in children, nor does it suggest immediate health risks. For medical advice or concerns about genetic health, please consult a qualified healthcare professional. For more details, refer to the original study: O. Isaac Garcia-Salinas et al, Nature Communications (2025), DOI: 10.1038/s41467-025-59750-x.
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