The attitude of millennials on homosexual behavior results from an relentless, rabidly intense propaganda effort by the entertainment and educational media for the past twenty years.
It has been a stupendously successful attempt at social engineering that did not originate in the American psyche.
It has been foisted off on Americans, and they have been conned into taking ownership of it.
I read an article back in the late 1990s where "activists" laid out what they were going to do, and bragged about it.
I still remember that article.