Societies socialize children about many things, including sex. Socialization is costly. It uses scarce resources, such as time and effort. Parents weigh the marginal gains from socialization against its costs. Those at the lower end of the socioeconomic scale indoctrinate their daughters less than others about the perils of premarital sex, because the latter will lose less from an out-of-wedlock birth. Modern contraceptives have profoundly affected the calculus for instilling sexual mores, leading to a de-stigmatization of sex. As contraception has become more effective there is less need for parents, churches and states to inculcate sexual mores. Technology affects culture.Lemma One is called "Lustful males": as women bear the costs of unwanted pregnancy, males will have a lower libido threshold for engaging in premarital activities.
They also suggest that church prohibitions on pre-marital sex loosened as churches became less likely to bear the costs of raising abandoned babies.