The family relationship can greatly influence antecedents. If teens feel parental support, feel a connection to their parents, and are aptly supervised by them, they are less likely to have unprotected sex and become pregnant. (Kirby, 2002). Both male and female teens postponement of sexual intercourse and consistent contraceptive use is related to parent-child connectedness. Parental monitoring, which consists of having routines and household responsibilities, and supervision of dating, has been shown to be a protective factor. Monitoring has been associated with teens not engaging in sex, postponing sex, or having fewer sexual partners. Indirectly, parental monitoring may prevent pregnancy by keeping their child away from high-risk peers. Overpowering maternal control on the other hand is related to an early first age in sexual intercourse. Parental psychological control is also related to high-risk behaviours among female teens. (Miller, 2002)
If parental rejection has been experienced, ranging from disinterest to hostility, it could lead to an exploration of fulfilling relationships outside of the immediate family. Parental rejection has been shown to be more indicative of adolescent problem behaviours than family religion, amount of parental control, family conflict, or organization. ( McCullough and Scherman, 1991) If parents model sexual risk taking behaviour, such as having given birth early, having relationships outside of marriage, or permissive attitudes about premarital sex, teens are more likely to engage in unprotected sex. Siblings can also model such behaviours and if a sibling has given birth at an early age it is more likely for the adolescent to engage in unprotected sex and become pregnant themselves. (Kirby, 2002).
Another family influence on adolescent sexual behaviour can be genetic or biological variables. Hormone levels and the timing of puberty, which can affect sexual behaviour, are partially hereditary. If a mother was young at her first intercourse it is more likely that both sons and daughters will have sex before age 14. Research as well as theory suggest that early onset of pubertal development is a significant predictor of early intercourse, which in turn is linked with irresponsible contraceptive use. (Miller, 2002).