Pioneering study finds generational link between smoking and body fat

Women and girls whose grandfathers or great-grandfathers began smoking at an early age tend to have more body fat, research that taps into the extraordinary 30-year-old Children of the 90s study has found.

In an earlier piece of work it was discovered that if a father started smoking regularly before reaching puberty, then his sons, but not daughters, had more body fat than expected.

Now researchers believe they have pinpointed higher body fat in females with grandfathers or great-grandfathers who began smoking before the age 13. No effects were observed in male descendants.

The research suggests exposure to substances can lead to changes that may be passed through the generations, though the team behind the research concede that much more work is needed to confirm this and understand how it may happen.

They have been able to spot the possible link because of the detail and depth of inter-generational data the University of Bristol study provides and it is an example of findings that the scientists could not have anticipated when it was launched in 1991.

Prof Jean Golding, the founder of Children of the 90s and lead author of the latest report, praised the participants in the study – an original cohort of 14,000 pregnant women who agreed to take part plus, now, their children and grandchildren.

Other pieces of research over the decades that could not have been foreseen include the finding 20 years ago that women who eat oily fish during pregnancy, even only once every two weeks, have children with sharper eyesight. This was believed to be the first time diet in pregnancy was shown to be associated with a child’s visual development.

A study published in 2013 concluded that iodine deficiency in pregnancy could have an adverse effect on children’s mental development. The discovery was made possible because the study had urine samples from early in participants’ pregnancies and detailed records of what the expectant mothers were eating.

Yet another finding was that early signs of a genetic liability to Type 2 diabetes could be spotted in children as young as eight and a link was also made between peanut allergies and skin cream containing peanut oil. The Children of the 90s project has even allowed experts to examine how wounds heal by looking at participants’ BCG vaccine scars.

For the latest study, published in the journal Scientific Reports, researchers dug into data on the smoking experiences of grandfathers and great-grandfathers. They could not look into the smoking of grandmothers and great-grandmothers as so few smoked, but were confident they would have reasonably reliable data from the male side of the family because they were likely to boast about smoking at a very young age.

Golding said: “This research provides us with two important results. First, that before puberty, exposure of a boy to particular substances might have an effect on generations that follow him. Second, 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.”

Golding said animal experiments had shown that exposure of males to certain chemicals before breeding can have effects on their offspring but there has been doubt as to whether this phenomena is present in humans.

“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. There is a heck of a lot more to discover,” Golding said.