Ancestral childhood environmental exposures occurring to the grandparents and great-grandparents of the ALSPAC study children

A history of asthma may be associated with grandparents' exposures to stress and cigarette smoking

Introduction: Within human epidemiological studies, associations have been demonstrated between grandparental exposures during childhood and grandchildren's outcomes. A few studies have assessed whether asthma has ancestral associations with exposure to cigarette smoking, but results have been mixed so far. Material and methods: In this study we used four generations: (F0 great-grandparents, F1 grandparents, F2 parents, F3 study children) of the Avon Longitudinal Study of Parents and Children (ALSPAC) to determine whether there is evidence of associations between asthma in generations F2 or F3 and exposures to severe trauma in childhood and/or active cigarette smoking during the adolescence of grandmothers and grandfathers in generations F0 and F1 respectively, or of a history of a F0 or F1 grandmother smoking during pregnancy. Results: We have shown that: a) stress exemplified by the death of a F1 grandparent's parent during the grandparents' childhood was associated with increased risk of asthma in generation F3, especially if the grandparent involved was the paternal grandmother; b) if the grandparents of generations F0 or F1 smoked during adolescence (i.e. < 17 years), their grandchildren in generations F2 and F3 were more likely to have a history of asthma; c) paternal F1 grandmother's smoking in pregnancy was associated with her F3 grandchild's asthma at age 7; d) There were differences between the results for the grandsons and granddaughters of the paternal grandmother with exposure to smoking in adolescence and with smoking in pregnancy. e) The addition of all of the individual exposure variables to the different analyses often provided a considerable increase in goodness of fit compared with only adding demographic factors associated with asthma at P < 0.10 such as social class; this was particularly true when all four exposure variables were combined in one model, suggesting possible synergistic effects between them. Discussion: We have shown associations between all four types of exposure to the grandparents to be associated with asthma in the grandchildren, such that the results both depended on whether the male or female line was involved, and the sex of the grandchildren. It was notable that the paternal grandmother was particularly involved in many of the associations. We emphasize that these are exploratory analyses, that asthma diagnostic criteria likely changed over time and may not be consistent between generations, and that the results should be tested in other cohorts.

Regular smoking of male ancestors in adolescence and fat mass in young adult grandchildren and great-grandchildren

Background: Previous studies using the Avon Longitudinal Study of Parents and Children (ALSPAC) have shown that if men commenced smoking prior to the onset of puberty their sons, their granddaughters and great-granddaughters were more likely to have excess fat (but not lean) mass during childhood, adolescence and early adulthood. In this study we assess associations between ancestral smoking during adolescence (ages 11-16 years) with fat and lean mass of subsequent generations at two ages. Methods: We analysed data on exposures of grandparents and great-grandparents collected by ALSPAC. The outcomes were the fat masses of their grandchildren and great-grandchildren measured at ages 17 and 24. Measures of lean mass were used as controls. Adjustment was made for 8-10 demographic factors using multiple regression. Results: We found associations between adolescent smoking of the paternal grandfathers and the adjusted fat mass of their grandchildren, but no associations with the grandchildren's lean mass. Grandchildren at age 17 had an average excess fat mass of +1.65 [95% CI +0.04, +3.26] Kg, and at age 24 an average excess of +1.55 [95% CI -0.27, +3.38] Kg. Adolescent smoking by the maternal grandfather showed similar, but weaker, associations: at 17 an average excess fat mass of +1.02 Kg [95% CI -0.20, +2.25] Kg, and at 24 an average excess of +1.28 [95% CI -0.11, +2.66] Kg. There were no pronounced differences between the sexes of the children. For the great-grandparents there were few convincing results, although numbers were small. Conclusions: We have shown associations between grandfathers' smoking in adolescence and increased fat (but not lean) mass in their children. Confirmation of these associations is required, either in a further data set or by demonstrating the presence of supportive biomarkers.

Possible transgenerational associations between grandparents’ childhood exposures and religious belief in their granddaughters: a longitudinal cohort study

Background: Research in non-genetic inheritance indicates that grandparents’ smoking habits and their childhood experiences of trauma can influence the physical and psychological attributes of their grandchildren. This was particularly apparent for outcomes such as autism and obesity where the population prevalence changed over time. Other factors which have changed temporally include religious and spiritual beliefs (RSBs) which have been declining in Western populations. Methods: We used data from the Avon Longitudinal Study of Parents and Children (ALSPAC) to explore whether grandparental exposures were associated with the religious and/or spiritual beliefs of their grandchildren as measured with a positive response to the question “Do you believe in God or some divine power?” . In line with other inter/trans-generational human studies we hypothesised that: (H1) grandparents’ childhood exposures to cigarette smoking (whether in utero or by active smoking) and/or exposure to traumatic events during childhood will be associated with their grandchild’s RSB; (H2) associations will differ between maternal and paternal lines of inheritance; (H3) relationships will vary with age at grandparental exposure, and (H4) associations will differ between grandsons and granddaughters. Results: We found significant associations between the grandchild’s RSB and both the grandparents’ smoking and their childhood trauma histories (H1 supported). These associations were mainly found down the maternal line (H2 possibly supported) and results varied with age of exposure of the grandparents; being strongest for in utero exposure of cigarette smoke and for pre-puberty exposure of traumatic events (H3 supported), and that granddaughters were more affected than grandsons (H4 supported). Conclusions: We hope that these results will motivate collection of similar data to further evaluate these questions in other populations, including a possible role for biological mechanisms.

Possible transgenerational associations between grandparents’ childhood exposures and religious belief in their granddaughters: a longitudinal cohort study

Background: Research in non-genetic inheritance indicates that grandparents’ smoking habits and their childhood experiences of trauma can influence the physical and psychological attributes of their grandchildren. This was particularly apparent for outcomes such as autism and obesity where the population prevalence changed over time. Other factors which have changed temporally include religious and spiritual beliefs (RSBs) which have been declining in Western populations. Methods: We used data from the Avon Longitudinal Study of Parents and Children (ALSPAC) to explore whether grandparental exposures were associated with the religious and/or spiritual beliefs of their grandchildren. In line with other inter/trans-generational human studies we predicted that: (P1) grandparents’ childhood exposures to cigarette smoking (whether in utero or by active smoking) and/or exposure to traumatic events during childhood will be associated with their grandchild’s RSB; (P2) associations will differ between maternal and paternal lines of inheritance; (P3) relationships will vary with age at grandparental exposure, and (P4) associations will differ between grandsons and granddaughters. Results: We found significant associations between the grandchild’s RSB and both the grandparents’ smoking and their childhood trauma histories (P1 supported). These associations were mainly found down the maternal line (P2 possibly supported) and results varied with age of exposure of the grandparents; being strongest for in utero exposure of cigarette smoke and for pre-puberty exposure of traumatic events (P3 supported), and that granddaughters were more affected than grandsons (P4 supported). Conclusions: We hope that these results will motivate collection of similar data to further evaluate these questions in other populations, including a possible role for biological mechanisms.

Regular smoking of male ancestors in adolescence and fat mass in young adult grandchildren and great-grandchildren

Background: Previous studies using the Avon Longitudinal Study of Parents and Children (ALSPAC) have shown that if men commenced smoking prior to the onset of puberty their sons, their granddaughters and great-granddaughters were more likely to have excess fat (but not lean) mass during childhood, adolescence and early adulthood. In this study we assess associations between ancestral smoking during adolescence (ages 11-16 years) with fat and lean mass of subsequent generations at two ages. Methods: We analysed data on exposures of grandparents and great-grandparents collected by ALSPAC. The outcomes were the fat masses of their grandchildren and great-grandchildren measured at ages 17 and 24. Measures of lean mass were used as controls. Adjustment was made for 8-10 demographic factors using multiple regression. Results: We found associations between adolescent smoking of the paternal grandfathers and the adjusted fat mass of their grandchildren, but no associations with the grandchildren's lean mass. Grandchildren at age 17 had an average excess fat mass of +1.65 [95% CI +0.04, +3.26] Kg, and at age 24 an average excess of +1.55 [95% CI -0.27, +3.38] Kg. Adolescent smoking by the maternal grandfather showed similar, but weaker, associations: at 17 an average excess fat mass of +1.02 Kg [95% CI -0.20, +2.25] Kg, and at 24 an average excess of +1.28 [95% CI -0.11, +2.66] Kg. There were no pronounced differences between the sexes of the children. For the great-grandparents there were few convincing results, although numbers were small. Conclusions: We have shown associations between grandfathers' smoking in adolescence and increased fat (but not lean) mass in their children. Confirmation of these associations is required, either in a further data set or by demonstrating the presence of supportive biomarkers.

ALSPAC parents' descriptions of childhood stresses in their parents and grandparents

Background: There is evidence that childhood stresses or traumas influence individuals' descendants' health and wellbeing through epigenetic mechanisms. However, few longitudinal studies have details of such ancestral data. Methods: Nearly 7,000 parents of the original Avon Longitudinal Study of Parents and Children (ALSPAC) cohort completed questionnaires concerning their parents' and grandparents' childhoods. As part of a questionnaire validation exercise  we conducted recorded interviews with 100 of these parents. Here we describe some of the vivid accounts from these interviews of stresses encountered by the parents' ancestors. Results: The interviews provided insights into the childhoods of two previous generations of this cohort, most of whom had lived through one, if not two, World Wars. Many children were brought up, not by their parents but by relatives or acquaintances and/or left home very young to 'go into service' or start work. A few interviewees had wealthy relatives with nannies and governesses and attended expensive boarding schools but by far the most frequent accounts were of poverty, often severe, with related lack of education and illiteracy, alcoholism and violence, alongside devastating effects of the World Wars. Conclusions: Although the interviews focussed on stresses in childhood and therefore the accounts seemed somewhat negative, many interviewees described their relatives as having secure, stable childhoods. Of the many struggling families though, the predominant impression was their remarkable resilience; all went on to have children or grandchildren who are stable enough to participate for three decades, entirely altruistically, in ALSPAC.

Human transgenerational observations of regular smoking before puberty on fat mass in grandchildren and great-grandchildren

Previously, using data from the Avon Longitudinal Study of Parents and Children (ALSPAC) we showed that sons of fathers who had started smoking regularly before puberty (< 13 years) had increased fat mass during childhood, adolescence, and early adulthood. We now show that if the paternal grandfather had started smoking pre-puberty, compared with later in childhood (13–16 years), his granddaughters, but not grandsons, had evidence of excess fat mass at two ages: mean difference + 3.54 kg; (P with 1-tailed test) = 0.043 at 17 years, and + 5.49 kg; (P₁ = 0.016) at age 24. When fathers of maternal grandfathers had started smoking pre-puberty, their great-granddaughters, but not great-grandsons, had excess body fat: + 5.35 kg (P₁ = 0.050) at 17, and + 6.10 kg (P₁ = 0.053) at 24 years. Similar associations were not found with lean mass, in a sensitivity analysis. To determine whether these results were due to the later generations starting to smoke pre-puberty, further analyses omitted those in subsequent generations who had smoked regularly from < 13 years. The results were similar. If these associations are confirmed in another dataset or using biomarkers, this will be one of the first human demonstrations of transgenerational effects of an environmental exposure across four generations.

Ancestral smoking and developmental outcomes: a review of publications from a population birth cohort†

The adverse effects on the child of maternal smoking in pregnancy is well-recognized, but little research has been carried out on the possible non-genetic effects of ancestral smoking prior to the pregnancy including parental initiation of cigarette smoking in their own childhoods or a grandmother smoking during pregnancy. Here, we summarize the studies that have been published mainly using data from the Avon Longitudinal Study of Parents and Children. We demonstrate evidence that ancestral smoking prior to or during pregnancy can often be beneficial for offspring health and both ancestor- and sex-specific. More specifically, we report evidence of (i) adverse effects of the father starting to smoke pre-puberty on his son's development; (ii) beneficial effects on the grandson if his maternal grandmother had smoked in pregnancy; and (iii) mainly adverse effects on the granddaughter when the paternal grandmother had smoked in pregnancy. The ancestor- and sex-specificity of these results are consistent with earlier studies reporting associations of health and mortality with ancestral food supply in their parents' and grandparents' pre-pubertal childhoods.

ALSPAC parents' descriptions of childhood stresses in their parents and grandparents

Background: There is evidence that childhood stresses or traumas influence individuals' descendants' health and wellbeing through epigenetic mechanisms. However, few longitudinal studies have details of such ancestral data. Methods: Nearly 7,000 parents of the original Avon Longitudinal Study of Parents and Children (ALSPAC) cohort completed questionnaires concerning their parents' and grandparents' childhoods. Validation of these questionnaires involved conducting recorded interviews with 100 of these parents. Results: The interviews provided insights into the childhoods of two previous generations of this cohort, most of whom had lived through one, if not two, World Wars. Many children were brought up, not by their parents but by relatives or acquaintances and/or left home very young to 'go into service' or start work. A few interviewees had wealthy relatives with nannies and governesses and attended expensive boarding schools but by far the most frequent accounts were of poverty, often severe, with related lack of education and illiteracy, alcoholism and violence, alongside devastating effects of the World Wars. Conclusions: Although the interviews focussed on stresses in childhood and therefore the accounts seemed somewhat negative, many interviewees described their relatives as having secure, stable childhoods. Of the many struggling families though, the predominant impression was their remarkable resilience; all went on to have children or grandchildren who are stable enough to participate for three decades, entirely altruistically, in ALSPAC.