A new study suggests that mothers’ genes may have a greater influence on their children’s body weight than previously thought — even when those genes are not directly passed on.
The research, published in the journal PLOS Genetics, found that maternal genetics play a significant role in shaping a child’s body mass index (BMI), not just through inheritance but also by influencing the environment in which the child develops.
Researchers from University College London analysed genetic and health data from over 2,600 families in the UK whose children were born in 2001 and 2002. The study followed the children from birth to age 17, allowing scientists to compare inherited DNA with the genetic traits of the parents that were not passed down.
Lead author Liam Wright explained that while both parents contribute equally to a child’s DNA, mothers may have a unique indirect impact on their child’s weight. “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,” Wright said.
This indirect effect is referred to as “genetic nurture” — a concept that includes how a parent’s own genes shape behaviours, health habits, and pregnancy conditions that, in turn, influence the child’s development.
The study found that both parents’ BMI played a role in predicting a child’s weight. However, fathers’ influence was mostly tied to the genes they passed on, while mothers had an additional impact likely driven by their own health, diet, and behaviours during pregnancy and early parenting.
The findings come amid growing concerns over childhood obesity, which has become a major public health challenge globally. In the UK, one in five children are overweight or obese by the time they start primary school, a figure that rises significantly by adolescence.
Wright emphasised that the study should not be viewed as placing blame on mothers but rather as a guide to understanding how maternal health can shape long-term outcomes for children. “This isn’t about blaming mothers, rather, supporting families to make a meaningful difference to children’s long-term health,” he said.
The authors suggest that interventions aimed at improving maternal health, particularly during pregnancy, could help reduce the risk of obesity being passed from one generation to the next.
“Targeted interventions to reduce maternal BMI, particularly during pregnancy, could reduce the intergenerational impacts of obesity,” Wright added.
