Reading the Wiki page for the US/UK counterculture of the 1960s, we come across this item:
The availability of new and more effective forms of birth control was a key underpinning of the sexual revolution. The notion of "recreational sex" without the threat of unwanted pregnancy radically changed the social dynamic and permitted both women and men much greater freedom in the selection of sexual lifestyles outside the confines of traditional marriage. With this change in attitude, by the 1990s the ratio of children born out of wedlock rose from 5% to 25% for Whites and from 25% to 66% for African-Americans
Which does strike me as funny - intentionally or otherwise. I don't think the following precis is unfair:
Sex "without the threat of unwanted pregnancy" permitted people much greater freedom in the selection of lifestyles outside marriage. Thus the ratio of children born out of wedlock at least tripled.
Not sure how much more obvious I can make it.