Breeding Research

"... Australian data indicate an even larger Cinderella effect... the estimated relative risk from stepfathers vs genetic fathers exceeds 300-fold... U.S. stepparents... in combination with population-at-large estimates suggest that stepchildren incurred such deaths at about 100 times the rate for same-age children living with two genetic parents... interviewed a select sample of well-established, “successful”, middle class, registered-marriage U.S. stepfamilies, and reported that only 53% of the stepfathers and 25% of the stepmothers felt able to say that they had any “parental feeling” (much less “love”) for their stepchildren... "

"A high proportion did not start using birth control until some time after first intercourse, however: On average, the delay between first coitus and first contraceptive use was eight months, and one-fifth of the respondents said that they began using a method only after their first pregnancy. Most of the women who did use a method at the time of first intercourse relied on the condom or withdrawal; in contrast, about two-thirds of white women and three-quarters of black women now rely on the pill, IUD or sterilization. Eighty-six percent of the women who had intercourse in the four weeks before the interview were current users--88 percent of the white women and 77 percent of the black women...

Thirty-three percent of unmarried 20-29-year-olds have had at least one pregnancy (about 40 percent of those who have ever had intercourse). Thirty-two percent of sexually active white women have been pregnant, compared with 70 percent of comparable black women. Furthermore, whereas 14 percent of white 20-29-year-olds have had an out-of-wedlock birth, 62 percent of black women have done so. The findings indicate that young, unmarried white women are far more likely than comparable black women to have an abortion. As might be expected, the large majority of pregnancies and births among these women are unwanted--80 percent of all pregnancies and 72 percent of all births."

"Pregnancy ambivalence, or unresolved or contradictory feelings about whether one wants to have a child at a particular moment, is one of the few psychosocial characteristics that have been identified as strong correlates of contraceptive practices... Imagining a pregnancy with a partner, even if a baby is not fully intended, may increase intimacy within the couple or help a woman appraise her current partner or relationship... Pregnancy ambivalence may also capture individuals with a passive orientation toward pregnancy— those who are “not not trying to get pregnant... Studies of adolescents demonstrate lower use of contraceptives among young women classified as ambivalent about pregnancy than among those with clear intentions... In fact, in that study, pregnancy ambivalence was more strongly associated with contraceptive practices than was a fatalistic attitude about pregnancy, provider satisfaction, race and ethnicity, parity, marital status or poverty level..."

"Although the cyclic shifts in women’s preferences on men’s traits signaling genetic quality are well supported by experimental evidence, studies testing whether women’s preferences on culturally based traits change with cycle are lacking... We also found that when the women’s fertility was at its highest, they preferred males with less body hair and that postmenopausal women demonstrated stronger preferences relating to male body hair than did premenopausal women... This suggests that women’s preferences as to male hairiness may be partly the result of sexual imprinting on paternal body hair and/or that this preference is heritable."

"Secondary sexual characteristics may indicate quality of the immune system and therefore a preference for masculinity may confer genetic benefits to offspring; however, high masculinity may be associated with costs of decreased paternal investment... We found that preferences for masculinity are increased when women either have a partner or are considering a short-term relationship... We also found that individuals using oral contraception do not show the above effects, indicating that such hormonal intervention potentially disrupts women’s choices for evolutionarily relevant benefits from males."

"Female respondents in the follicular phase of their menstrual cycle... were significantly more likely to choose a masculine face than those in menses and luteal phases... This study provides further evidence that when conception is most likely, females prefer testosterone related facial characteristics that may honestly advertise immunocompetence."

"Results indicated that normally cycling (non–pill using) women near the peak fertility of their cycle tended to prefer the scent of shirts worn by symmetrical [very biologically attractive face] men. Normally ovulating women at low fertility within their cycle, and women using a contraceptive pill, showed no significant preference for either symmetrical or asymmetrical men's scent."