Although probably young people do explore, from everything I have read or heard from older people, exploration of sex with the same gender (for all except those who identified as homosexual) did occur , but was extremely rare.
To my thinking there is no doubt but that the LGBTQ promotion/teaching/acceptance/celebration in the schools, universities, media, entertainment has made a huge difference. Anyone who taught teens-college-aged students in the 70s - or was a teen then - and then again in the late '90s up to now, can see the difference.