Age at First Sexual Intercourse and Teenage Pregnancy in Australian Female Twins

Waldron, Mary; Heath, Andrew C.; Turkheimer, Eric; Emery, Robert E.; Bucholz, Kathleen K.; Madden, Pamela A. F.; Martin, Nicholas G.

doi:10.1375/twin.10.3.440

Cited by 13 publications

(8 citation statements)

References 57 publications

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“…Second, controlling for a measure of alcohol dependence (the ADS) did not diminish the association. Third, the greater genetic effect in the Anglo/White sample is consistent with prior studies in healthy children and adolescents showing greater heritability in higher SES groups [52], [53], [61]. In light of these findings, we have no reason to believe that the associations we observed will not generalize to healthy populations.…”

Section: Discussionsupporting

confidence: 88%

Rare Copy Number Deletions Predict Individual Variation in Intelligence

et al. 2011

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Phenotypic variation in human intellectual functioning shows substantial heritability, as demonstrated by a long history of behavior genetic studies. Many recent molecular genetic studies have attempted to uncover specific genetic variations responsible for this heritability, but identified effects capture little variance and have proven difficult to replicate. The present study, motivated an interest in “mutation load” emerging from evolutionary perspectives, examined the importance of the number of rare (or infrequent) copy number variations (CNVs), and the total number of base pairs included in such deletions, for psychometric intelligence. Genetic data was collected using the Illumina 1MDuoBeadChip Array from a sample of 202 adult individuals with alcohol dependence, and a subset of these (N = 77) had been administered the Wechsler Abbreviated Scale of Intelligence (WASI). After removing CNV outliers, the impact of rare genetic deletions on psychometric intelligence was investigated in 74 individuals. The total length of the rare deletions significantly and negatively predicted intelligence (r = −.30, p = .01). As prior studies have indicated greater heritability in individuals with relatively higher parental socioeconomic status (SES), we also examined the impact of ethnicity (Anglo/White vs. Other), as a proxy measure of SES; these groups did not differ on any genetic variable. This categorical variable significantly moderated the effect of length of deletions on intelligence, with larger effects being noted in the Anglo/White group. Overall, these results suggest that rare deletions (between 5% and 1% population frequency or less) adversely affect intellectual functioning, and that pleotropic effects might partly account for the association of intelligence with health and mental health status. Significant limitations of this research, including issues of generalizability and CNV measurement, are discussed.

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Section: Discussionsupporting

confidence: 88%

Rare Copy Number Deletions Predict Individual Variation in Intelligence

et al. 2011

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“…Second, the claim that FTA studies 'prove' that a disorder is 'biological' is weak. An astonishingly wide array of human behaviors and traits, such as hours spent watching television, 10 sports participation, 11 church attendance, 12 doing crossword puzzles, 13 age at first sexual intercourse 14 and liking roller coasters, 13 are heritable. Turkheimer 1 has suggested a first law of behavior genetics: 'All human behavioral traits are heritable'.…”

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confidence: 99%

What psychiatric genetics has taught us about the nature of psychiatric illness and what is left to learn

Kendler

2013

Mol Psychiatry

168

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Psychiatric genetics has taught us a great deal about the nature of psychiatric disorders. Traditional family, twin and adoption studies have demonstrated the substantial role of genetic factors in their etiology, clarified the role of genetic factors in comorbidity, elucidated development pathways, and documented the importance of gene-environment correlation and interaction. We have also received some hard lessons when we were unable to detect replicable genes of large effect size and found that our much-valued candidate genes did not live up to their expected promise. With more mature molecular and statistical methods, we are entering now a different era. Statistical analyses of aggregate molecular signals are validating earlier heritability estimates. Replicated findings from genome-wide association studies are beginning to emerge, as are discoveries of large-effect size rare genomic variants. The number of such findings is likely to soon grow dramatically. The most pressing question facing the field is what biological picture these results will reveal. I articulate four possible scenarios that reflect (i) no, (ii) minimal, (iii) moderate and (iv) high biological coherence in the replicated molecular variant findings, which are soon likely to emerge. I discuss the factors that will likely influence these patterns, including the problems of etiological heterogeneity and multiple realizability. These findings could provide critical insights into the underlying biology of our psychiatric syndromes and potentially permit us to perceive, 'through a glass darkly,' the levels of the mind-brain system that are disordered.

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“…Previous behavioral genetic research indicates that age at first sexual intercourse (AFS) is partially heritable, meaning that a proportion of the observable differences in AFS between individuals within a population can be attributed to genetic differences (see Harden, 2013, for a review). The magnitude of heritability estimates for AFS has varied, ranging from relatively modest (.24–.36; e.g., Lyons et al, 2004; Segal & Stohs, 2009; Waldron et al, 2007) to quite substantial (.49–.72; e.g., Dunne et al 1997; Mustanski, Viken, Kaprio, Winter, & Rose, 2007). There is also evidence for both cohort and gender effects.…”

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confidence: 99%

Early adverse environments and genetic influences on age at first sex: Evidence for gene × environment interaction.

Carlson

Mendle

Harden

2014

Developmental Psychology

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Youth who experience adverse environments in early life initiate sexual activity at a younger age, on average, than those from more advantaged circumstances. Evolutionary theorists have posited that ecological stress precipitates earlier reproductive and sexual onset, but it is unclear how stressful environments interact with genetic influences on age at first sex. Using a sample of 1,244 pairs of twins and non-twin full siblings from the National Longitudinal Study of Adolescent Health, the present study tested for gene-by-environment interactions (G × E) on age at first sex (AFS). Multivariate interaction models indicated that genetic influences on AFS were suppressed among low-socioeconomic-status (SES) and ethnic-minority compared with higher SES and ethnic-majority youth. Father absence did not uniquely moderate genetic influences on AFS. These results are broadly consistent with previous findings that genetic influences are minimized among individuals whose environments are characterized by elevated risk; however, future research would benefit from samples with larger numbers of individuals at the very low end of the SES spectrum.

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Age at First Sexual Intercourse and Teenage Pregnancy in Australian Female Twins

Cited by 13 publications

References 57 publications

Rare Copy Number Deletions Predict Individual Variation in Intelligence

Rare Copy Number Deletions Predict Individual Variation in Intelligence

What psychiatric genetics has taught us about the nature of psychiatric illness and what is left to learn

Early adverse environments and genetic influences on age at first sex: Evidence for gene × environment interaction.

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