This theory was preceded by over a century where biological essentialism was the dominant paradigm on race. Biological essentialism is the belief that white European races are biologically superior and other non-white races are inherently inferior. This view arose as a way to justify slavery of Africans and genocide of the Native Americans in a society which was supposedly founded on freedom for all. This was a notion that developed slowly and came to be a preoccupation of scientists, theologians, and the public. Religious institutions asked questions about whether there had been multiple genesis's (polygenesis) and whether God had created lesser races of men. Many of the foremost scientists of the time took up idea of racial difference. They would inadvertently find that white Europeans were superior. One method that was used was the measurement of cranial capacity. 
A lot of it must come down to how young girls are overly sexualized by the media, and put under pressure to become sexually active at a young age. Education also puts too much emphasis on just girls, and reinforces the fact that it is the mothers that are usually blamed for teen pregnancy while the fathers often take no responsibility and get away with it. Young men need to know that they can’t behave in this way, and understand the pressures of becoming a father, while girls need to become more assertive and be able to demand the use of contraception even if they’re drunk and their partner doesn’t want to use it.