Smoking may make your children obese
Kat - UK scientists have shown that fathers who started smoking before puberty producesons that are more likely to be overweight. Very confusing. Bristol researcher Marcus Pembrey led the study and he joins us now to explain more. What are you trying to find out that led to this study?
Marcus - Well, we're basically interested in the possibility that some of our inheritance might go beyond the genome and be rooted in early life parental and ancestral experience, a sort of transgenerational response system.
Kat - So, things that your parents do or your grandparents did are reflected in your own self then.
Marcus - That's true. We were able to ask some questions along these lines. In the children of the '90s study in Bristol, this is the world's most comprehensive follow up in terms of detail of 14,000 children and thir mothers who were born in '91, '92. They were ascertained in pregnancy and of course, they're now 22, 23. In all that time, we've collected an enormous amount of information, genetics, measurements, diet, everything else.
Kat - So tell me a bit about this particular link with smoking. So, who were you looking at what did you find?
Marcus - Well, what we were trying to do was to test a hypothesis that was generated by some earlier Swedish studies that showed that period before puberty, mid-childhood was an exposure sensitive period with respect to these transgeneration effects down the male line, through the father. So, what we were doing was, we got information on when the fathers and the mothers actually started smoking. Although we had about 10,000 fathers responded, half of them had smoked at some time, 3% 166 had started before the age of 11. So, those are the ones we were interested in their offspring.
Kat - So then, what did you find about the offspring of those particular dads?
Marcus - Well, we analysed the boys and girls separately and we found that the sons, by the time they were in their teenage years - from 13 to 17 - had much larger BMI than the comparison group. The comparison group were all the others, the sons of fathers who started smoking after the age of 11 and also, the sons of fathers who didn't smoke at all.
Kat - This does sound quite strange. What do you think is actually going on? Do you think that there's something else happening that's influencing this or is it some kind of effect of the chemicals in the cigarette smoke at that group of time?
Marcus - Well, there are about 2,000 chemicals in cigarette smoke, so we don't know, but we know it has a big biological effect, smoking. It seems that something is being transmitted through the reproductive system. The exposure before puberty gets under the skin in some way in endures. It affects the reproductive system, probably carried by sperm to the son, but could be - I don't know - through the seminal fluid. In humans, we don't know what the mechanism is.
Kat - Thanks very much. That's Marcus Pembrey whose research is published in the European Journal of Human Genetics this week.