When I grew up, sexuality was considered by the masses as binary. You were gay or straight. Society, in all of its anxiety felt the need to put people into a set category.
It’s not true for all people, in fact not true for most people.
People fall into a continuum, very few people are 100% heterosexual, and very few are 100% homosexual. It looks that way due to the social pressure that pushed weaker individuals into categories.
Look at what happens when people are forced into single sex situations. The majority will eventually turn to each other for sexual release, when they could just masterbate.
Finally the new generation is acknowledging this fact.
It’s not a “contagion”, it’s people being free to be themselves and not conform to societal expectations.
https://www.washingtonexaminer.com/...say-they-are-lgbt-suggesting-social-contagion