Why does early sexual intercourse predict subsequent maladjustment? Exploring potential familial confounds.
OBJECTIVE
Previous studies have found an association between early age at first sexual intercourse and subsequent psychosocial maladjustment. Using a quasi-experimental approach, we examined the extent to which this observed association may be due to familial confounds not explored in prior research.


METHODS
Using a population-based cohort of Swedish adult twins (ages 19-47; N = 12,126), we examined the nature of the association between early sexual intercourse (i.e., first intercourse occurring before age 16) and various outcomes reflecting psychosocial health, including substance use, depression, criminal convictions, and adolescent childbearing. We used two methods--discordant-twin analyses and bivariate twin modeling--to estimate the extent to which genetic and environmental confounds explained observed associations.


RESULTS
Individuals who engaged in early intercourse were at greater risk for most of the adverse psychosocial health outcomes measured in this study. However, twin pairs discordant for engaging in early intercourse did not differ significantly in their risk for psychosocial maladjustment. Our results indicated that early age at first sexual intercourse and subsequent psychosocial maladjustment may be associated because of familial factors shared by twins.


CONCLUSIONS
Early intercourse may be associated with poor psychosocial health largely due to shared familial influences rather than through a direct causal connection. Therefore, effective and efficient interventions should address other risk factors common to early intercourse and poor psychosocial health.
Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405, USA. kldonahu@indiana.edu
Kelly L
KL
Donahue
Paul
P
Lichtenstein
Niklas
N
Långström
Brian M
BM
D'Onofrio
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D015331:Cohort Studies; D003075:Coitus; D057237:Criminals / Q000706:statistics & numerical data; D003863:Depression / Q000453:epidemiology; D004200:Diseases in Twins / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008297:Male; D011247:Pregnancy; D011253:Pregnancy in Adolescence / Q000706:statistics & numerical data; D012307:Risk Factors; D019966:Substance-Related Disorders / Q000453:epidemiology; D013548:Sweden / Q000453:epidemiology; D014427:Twins / Q000523:psychology*; D055815:Young Adult