Birth Order and First Sexual Experience:
Do Siblings Influence Sexual Debut in Adolescents?

Marta Pasqualini (Sciences Po - OSC), Amanda Sacker (University College of London)
& Anne McMunn (University College of London)

Archives of Sexual Behavior, The Official Pulication of the International Academy of Sex Research

First Published, 21 August 2021 (Open Access)

Authors explored the relationship between birth order, sex, timing of sexual initiation, and its consequences for risky sexual behavior and sexual health. They evaluated several research hypothesis. Data are drawn from the third UK National Survey of Sexual Attitudes and lifestyles. A selected sample of young adults aged 16-24 sexually active was build for face to face interviews and self-completion questionnaires. 

Birth order represents a social determinant of individual development, which strongly affects the propensity to adopt certain behaviors and attitudes. Empirical evidence has suggested that siblings are major socializing agents with regard to issues that are relevant for adolescents, such as the first sexual experience.

Whereas women born as only-children were more likely to sexually debut at later ages, middle-child boys were significantly more prone to initiate sexual intercourse earlier compared with first-borns. As expected, early sexual initiation was associated with riskier behaviors and sexual health outcomes.
Authors hypothesized that having a sister as the confidant concerning sexual issues would protect both men and women from adopting risky behaviors and contracting sexual diseases (“mentor effect”)... read here the full paper to consult the whole results and strengths.