For the first time, we were being asked to imagine ourselves as and to identify with The Other. During the civil rights marches, while our ears rang with Martin Luther King's dream, science fiction was telling us that The Other was human, too. The idea of alieness had suddenly become one of degree. The next tentative step down that road was the portrayal of aliens who were normal humans, biologically speaking, but who were raised by aliens and therefore not quite Establishment. Take for example all those films where a pregnant white woman is abducted by Apache.
Mother dies in childbirth.
In early SF, female characters served as the scientist's ignorant girlfriend, or the hero's reward for a job well done. But in the 1960s, in the real world, women began to protest this socialization. And so male SF writers, a bit puzzled, but game for the challenge, turned to an examination of who women might be. The women in these books were not fully human. In the late sixties and early seventies, women writers took over the job of talking about the alien.