Men who smoked before teens may father fatter sons

Smoking before puberty may lead to men fathering fatter sons, suggesting that lifestyle factors can have adverse impacts on the next generation, a study has found.

The research found that men who smoked regularly before age 11 fathered sons who had five to ten kilograms more body fat than the sons of men who did not smoke, or started smoking after age 11. The researchers said this could indicate that exposure to tobacco smoke before puberty might lead to epigenetic changes in metabolism in the next generation, passed on through the male line.

Senior author of the study, Professor Marcus Pembrey, said: 'This discovery of trans-generational effects has big implications for research into the current rise in obesity and the evaluation of preventative measures'. He added: 'It is no longer acceptable to just study lifestyle factors in one generation'.

A similar effect on increased Body Mass Index (BMI) was also observed in the daughters of fathers who smoked before age 11, but to a much lesser extent. However, no such association was found between when a mother started smoking and body fat of her children.

The results of this study should be interpreted with caution as the authors themselves state that there are a number of weaknesses in this study. In particular, less than one percent of all the fathers questioned started smoking regularly before age 11. Together these men fathered only 13 sons, leading some experts to comment on the significance of the findings based on the small sample size.

Dr Graham Burdge, researcher of human nutrition at the University of Southampton, told Reuters the findings 'may potentially provide new insights into factors that may influence development of obesity in childhood', but 'the findings only show associations and cannot be interpreted as indicating that paternal smoking at an early age causes obesity in their sons'.

He added that, 'A possible alternative interpretation is that that exposure of parent and child to a common environment has an effect on the child's BMI that might be influenced by the lifestyle of the father'.

Tim Spector, a professor of genetic epidemiology at King's College London, commented that: 'The data are persuasive but not yet definitive as we need to confirm the same smoking related epigenetics changes in the kids' DNA'.