Fathers’ Teenage Weight May Leave an Epigenetic Mark on Future Children

A father’s health before conception may play a larger role in a child’s future biology than once thought. While much attention has traditionally focused on maternal health during pregnancy, growing research suggests that a father’s early-life experiences may also influence the next generation through epigenetic changes.

A study from researchers at the University of Southampton and the University of Bergen found that boys who became overweight during early adolescence had children with epigenetic markers linked to obesity, asthma, and low lung function. The findings, published in Communications Biology, are the first human study to point to male puberty as a potentially important window when lifestyle and environmental factors may leave lasting biological signals in future sperm cells.

Epigenetics refers to changes in gene expression that affect how genes work without changing the DNA sequence itself. One common epigenetic mechanism is DNA methylation, which helps regulate whether certain genes are more or less active. These molecular marks do not rewrite the genetic code, but they can influence how cells respond to development, metabolism, inflammation, and environmental stress.

In this study, researchers analyzed epigenetic profiles from 339 individuals aged 7 to 51. They also assessed the fathers’ changes in body composition during adolescence using self-reported body image as a proxy for body fat. The strongest associations appeared around the time of voice break, a marker of male puberty.

The researchers identified more than 2,000 DNA methylation changes across 1,962 genes in children whose fathers gained weight as teenagers. Many of these genes were linked to adipogenesis, the formation of fat cells, and lipid metabolism, the way the body processes fats. Some of the methylation changes were also associated with asthma, body mass index, and lung function.

“The overweight status of future fathers during puberty was associated with a strong signal in their children’s DNA which were also related to the likelihood of their children being overweight themselves,” said Dr. Negusse Tadesse Kitaba, Senior Research Fellow at the University of Southampton.

The study also found that the effect was more pronounced in female children than in male children, though different genes appeared to be involved. This suggests that paternal puberty-related epigenetic effects may not affect all offspring equally. The findings do not mean that a father’s teenage weight determines a child’s health. Instead, it suggests that puberty may be a sensitive developmental period during which excess weight can become linked to epigenetic patterns later detectable in offspring. Because sperm development begins during puberty, this stage may be particularly vulnerable to environmental and lifestyle influences.

“Early puberty, when boys start their developing sperm, seems to be a key window of vulnerability for lifestyle influences to drive epigenetic changes in future offspring,” Kitaba said.

For epigenetics research, the study adds to evidence that inheritance is not only about DNA sequence. The way genes are regulated may also carry information shaped by development, environment, and timing. This is especially important for understanding complex health conditions such as obesity, asthma, and metabolic disease, where both inherited biology and life exposures may contribute to risk. The research also broadens how scientists think about adolescent health. Puberty is often viewed as a period that affects a person’s own development, but these findings suggest it may also have biological significance for future generations. As childhood and teenage obesity continue to rise globally, understanding these intergenerational effects could become increasingly important for public health.

The study provides another reminder that epigenetics is not destiny. Epigenetic patterns are part of a complex biological system influenced by many factors, including genetics, environment, nutrition, development, and lifestyle. But by identifying when and how these patterns may form, researchers can better understand how early-life exposures shape health across generations.

Source: Kitaba NT, et al. Father’s adolescent body silhouette is associated with offspring asthma, lung function and BMI through DNA methylation. Communications Biology. May 24, 2025.

Resource: University of Southampton. Boys who are overweight in their early teens risk passing on harmful epigenetic traits to future children. May 27, 2025.