Sons of Men Who Smoke at Young Age Have Higher BMIs

Men who started smoking regularly before age 11 were more likely to father heavier sons, according to research published in the April 2, 2014, issue of European Journal of Human Genetics.

Researchers from the University of Bristol in the United Kingdom studied 9,886 fathers enrolled in the University’s Children of the 90s study, of whom 5,376 (54%) were smokers at some point and 166 (3%) said they smoked regularly before age 11. The men’s sons’ body mass indexes (BMIs) were measured at ages 13, 15, and 17. Sons whose fathers had smoked before age 11 had higher BMIs than sons of men who had never smoked.

“This discovery of trans-generational effects has big implications for research into the current rise in obesity and the evaluation of preventative measures,” Marcus Pembrey, BSc, MD, the study’s senior author, said in a press release.“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.”

Though the most common age of smoking onset was 16 years, investigators chose to focus on age 11, when most men would be pre-puberty.

The study also found nearly half (46%) of the sons of fathers who started smoking before age 11 had themselves started smoking by age 17. Further analysis determined no association between age of smoking onset and their BMI.

Females were also evaluated in the study. Daughters of men who smoked before age 11 were also examined, and though they showed greater differences throughout points of adolescence, they were consistently less and did not reach statistical significance. Maternal smoking onset was recorded — 1% of smoking mothers reported beginning smoking before age 11 – but their sons or daughters showed no evidence of an increased mean BMI.

“We have shown that cigarette smoking in mid childhood represents a valuable model for future analysis of human transgenerational responses both in terms of molecular mechanisms and public health implications,” the authors wrote. “We have also shown that the effect on BMI and body fat is most pronounced in the sons, but cannot rule out a smaller effect in the daughters.”