A mother’s genes could play a role in determining a child’s future weight – more so than a father’s.
Researchers at University College London (UCL) investigated how a parent’s weight and genes influence their children’s weight and diet from birth to age 17.
To make the comparison, researchers used genetic and health data of 2,621 UK families in the Millennium Cohort Study, a UK birth cohort study of individuals born in 2001-2002.
The study, published in the journal PLOS Genetics, looked at the BMI of parents and the birthweight of their children. They also looked at the child’s diet at ages three, five, seven, 11, 14, and 17.
Children’s diets were assessed through self-reported records of how often and how much they consumed different food groups, including fruit, vegetables, fast food, and sugary drinks.
Researchers then separated the direct effects of inherited genes from the indirect effects of genes that were not inherited.
Study authors explained that non-inherited genes can still influence children’s outcomes by influencing the development environment, such as conditions in the womb and parenting practices, as these are shaped by parents’ genetics.
Analysis revealed that while both parents’ genetics influence a child’s BMI, a mother’s BMI continued to affect the child’s weight beyond direct genetic inheritance.
Researchers suggest this means genetic nurture, where a parent’s genes shape the environment they create for their child, might be a big factor in a child’s weight.
This could be the case if a mother’s genes influence her own weight, eating habits, or behaviours during pregnancy, which in turn can affect the child’s development and long-term health.
Dr Liam Wright, the study’s lead author, said: “Mothers’ genetics appear to play an important role in influencing their child’s weight over and above the child’s genetics.
“In addition to the genes mums directly pass on, our findings suggest that maternal genetics are instrumental in shaping the environment in which the child develops, therefore indirectly influencing the child’s BMI too.”
Almost a third of children aged two to 15 were considered to be obese or overweight in 2024, according to NHS data.
However, researchers acknowledge BMI is not the most accurate way of measuring body fat, particularly among children, and so supplemented their analysis with several other adiposity-related measures, including fat mass.
Dr Wright added: “This isn’t about blaming mothers, rather, supporting families to make a meaningful difference to children’s long-term health. Targeted interventions to reduce maternal BMI, particularly during pregnancy, could reduce the intergenerational impacts of obesity."
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