"There are of course many things which through lived experience going back thousands of years have shown themselves to be effective ways of handling certain issues, but like everything in the accepted scientific method, everything is a theory, to be accepted only until such time as something happens to prove that theory is incorrect."
Would you be happy to use the term 'traditions' to describe these things which were effective ways of handling certain issues? - have you ever heard of Chestertons fence?
"In practice this means, for example, that homosexual relationships or sex outside marriage between consenting and available adult partners is not harmful or wrong, because it has not been demonstrated that it is."
Isn't it more than technology has made it safer to have extramarital sex? Rather than some kind of "moral progress" and we've just discovered that it's no biggie? Because for a long time it was deemed wrong. And you wouldn't want your daughter having a multitude of varying casual partners. I imagine you still wouldn't.