Researchers at the University of Bristol and colleagues at the University College London analyzed data involving almost 10,000 fathers. Fifty-four percent were smokers and of these smokers, 3 percent said they smoked regularly before the age of 11.
The study, published in the European Journal of Human Genetics, found the sons of the early smokers had the highest body mass index -- 11 to 22 pounds heavier -- compared to the sons of men who started smoking later or who never smoked. The early smokers tended to have lower than average BMI as adults than the rest of the study participants. The daughters were also heavier but not to the extent of the sons.
"This discovery of trans-generational effects has big implications for research into the current rise in obesity and the evaluation of preventative measures," senior author Marcus Pembrey of the University College London said in a statement.
"It is no longer acceptable to just study lifestyle factors in one generation. We are probably missing a trick with respect to understanding several common diseases of public health concern by ignoring the possible effects of previous generations."
[European Journal of Human Genetics]