Genetic breeding or why maternal genes influence children's obesity

A mother's genes may play a bigger role in determining whether a child is overweight than a father's. The reason lies in a concept known as genetic nurture, according to a new study published in PLOS Genetics .

Led by researchers at the Institute for Social Research at University College London (UCL), the research analyzed genetic and health data from 2,621 UK families in the Millennium Cohort Study, a UK birth cohort study of individuals born in 2001/02.

Researchers analyzed how parents' body mass index (BMI) and related genes influence their children's weight and diet from birth to age 17.

To do this, the association between parental BMI and child birth weight, BMI, and diet was examined at six key points during childhood and adolescence: ages 3, 5, 7, 11, 14, and 17 years. Children's diets were assessed through self-reported records of the frequency and quantity they consumed different food groups, including fruits, vegetables, fast food, and sugary drinks.

By measuring the genes of both children and their parents, the researchers were able to separate the direct effects of inherited genes from the indirect effects.

Non-inherited genes can also influence child development by influencing the developmental environment, such as conditions in the womb and parenting practices, as these are influenced by the parents' genetics.

They discovered that, while both parents' BMIs were linked to their child's, the father's influence could be explained almost entirely by direct genetic inheritance. In contrast, the mother's BMI continued to influence the child's weight even after direct genetic inheritance.

This suggests, according to the researchers, that genetic nurture—where parents' genes shape the environment they create for their child—could be at play. For example, a mother's genes could influence her own weight, eating habits, or behavior during pregnancy, which in turn affects her child's development and long-term health.

"In addition to the genes mothers pass on, our findings suggest that maternal genetics shape the environment in which children grow up, indirectly influencing their body mass index (BMI)," explains Liam Wright , the study's lead author.

Because BMI is an imperfect measure of body fat, especially in children, the team supplemented the analysis with other measures of adiposity, including fat mass.

Wright emphasizes that the goal is not to " blame mothers, but to support families to improve children's long-term health ." Thus, she adds, interventions aimed at reducing maternal BMI, particularly during pregnancy, could reduce the intergenerational impact of obesity.