Granddaughters and great-granddaughters of men who start to smoke before puberty, are likely to have more body fat than expected, according to a research.
The findings, published in the journal Scientific Reports, showed that higher body fat in females whose paternal grandfathers or great-grandfathers had started smoking before age 13 compared to those whose ancestors started smoking later in childhood (age 13 to 16).
The research shows that "before puberty, exposure of a boy to particular substances might have an effect on generations that follow him", said Professor Jean Golding, lead author of the study.
Importantly, "one of the reasons why children become overweight may be not so much to do with their current diet and exercise, rather than the lifestyle of their ancestors or the persistence of associated factors over the years", he added.
Previously experiments with model studies have shown that exposure of males to certain chemicals before breeding can have effects on their offspring. There has, however, been doubt as to whether this phenomena is present in humans and whether any apparent effects may be more readily explained by other factors.
To investigate effects of prepubertal exposures in humans, scientists from the University of Bristol in the UK studied possible effects of ancestral prepubertal cigarette smoking on over 14,000 participants.
An earlier research from 2014, had shown that if a father started smoking regularly before reaching puberty (before 11 years of age), then his sons, but not his daughters, had more body fat than expected.
But, in the new study no effects were observed in male descendants. Increased body fat was found only in females whose grandfathers or great-grandfathers began smoking before puberty.
The researchers noted that the observations need to be confirmed in other longitudinal studies, and investigation must expand into other transgenerational effects and ancestral exposures.
Golding said: "If these associations are confirmed in other datasets, this will be one of the first human studies with data suitable to start to look at these associations and to begin to unpick the origin of potentially important cross-generation relationships."
