The Great Society policies of the greatest generation were done during the height of US prosperity and power. The failure of these policies were not seen until the next generation who chose to expand and perpetuate those policies. It was the Boomers that made drug use, promiscuity, divorce, co-habitation, single parenthood socially acceptable and gave us the “Me Generation” of the 80’s.
You must not have heard of the "Beatnik Generation". And it was the Great Society welfare programs passed in 1965 by the GG that paid single mothers with children enough to live on, and that ushered in single parenthood and the absence of fathers, and the still growing out-of-wedlock birthrate.
Sexual promiscuity was never as rare as some want to believe, and the birth control pill which became available in the mid-'60s is more responsible for changes in sexual behavior than anything else. That was hardly generational behavior as the first customers for the new pills would have been non-boomer adults of the 1960s.
The programs passed in 1965 that paid women to have children out-of-wedlock, and the birth control pill brought about the changes you mention, not the boomer generation.
And Rock-and-Roll, teenage rebellion and juvenile delinquency also preceded the boomers.