A twin study of sexual behavior in men.
The role of genetic and environmental influences on age of initiation of first sexual relations and engaging in sexual activity with multiple partners (10 or more partners in 1 year) was investigated in male twins (N = 6,744) from the Vietnam Era Twin Registry. Individual differences in both types of sexual behaviors were heritable, but only age of onset of sexual relations was significantly influenced by the environment shared by the twins. There was a moderate negative correlation between age of initiation of sexual relations and the multiple partners variable; initiating sexual relations earlier was associated with a higher probability of having multiple partners. The additive genetic influence on age of initiation also influenced the multiple partners variable. The substantial unique environmental influences on each variable were uncorrelated with each other. The data suggest that the observed association between age of initiation of sexual relations and having multiple partners is due to genetic influences common to both behaviors.
Lyons
Michael J
MJ
Department of Psychology, Boston University, Boston, Massachusetts 02215, USA. mlyons@bu.edu
Koenen
Karestan C
KC
Buchting
Francisco
F
Meyer
Joanne M
JM
Eaves
Lindon
L
Toomey
Rosemary
R
Eisen
Seth A
SA
Goldberg
Jack
J
Faraone
Stephen V
SV
Ban
Rachel J
RJ
Jerskey
Beth A
BA
Tsuang
Ming T
MT
D000328:Adult; D000367:Age Factors; D003075:Coitus / Q000523:psychology; D018451:Homosexuality, Male / Q000235:genetics / Q000523:psychology* / Q000706:statistics & numerical data; D006801:Humans; D007398:Interpersonal Relations; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012042:Registries; D012747:Sexual Partners / Q000523:psychology; D014427:Twins; D014481:United States / Q000453:epidemiology