Overweight/Obesity and Ancestral Environmental Smoking Exposures: A Summary of Results from the ALSPAC Cohort

There is considerable discussion concerning the recent increase in the prevalence of overweight/obesity in children and adults. Although it is assumed that current diet and sedentary behavior are key contributors, these factors do not seem to be the only characteristics responsible. In this paper we summarize the findings we have obtained when assessing whether exposures in previous generations may have played a part in this change over time. In particular, we show that ancestral smoking may be an important contributor. We used data collected from parents and grandparents by the Avon Longitudinal Study of Parents and Children (ALSPAC), which has followed children born in 1991-1992 to women resident in south-west England. We have shown that ancestral smoking characteristics were associated with fetal growth and with increased measures of adiposity in their children and grandchildren. Here we describe the detailed findings of the ancestral exposure to cigarette smoking of ancestors at various time points using ALSPAC data and indicate the support for the findings in other cohorts. Since body mass index (BMI) can be a measure of lean (muscle) mass as well as fat mass, we concentrate on associations with body composition from dual-energy x-ray absorptiometry (DXA). Few birth cohorts have collected data on smoking of individuals in the male line and few have used details of fat, bone, and lean mass. Findings concerning grandmaternal smoking in pregnancy and pre-pubertal smoking of male ancestors were nevertheless replicated. We consider the likelihood of epigenetic explanations for these findings.