The question is what they'll take out with them when they do fail.

Indeed. So provide some evidence they'll take anything out.

No, heterosexuality (and monogamy) is right because it is an effective system for raising children.

There's no logical connection between "X is effective at Y" and "X is mandatory on everybody".

The existence of celibate priests , spinsters and other non breeders has not historically destroyed any societies.

It will convert some people and cause others to mess up their lives. Also what these "find out if you're gay" > programs are doing is much more than "a rumour of an alternative".

Evidence...evidence...and evidence?

(And notice how anomalous your claims are. In every other case, everybody, including conservatives, can understand the difference between teaching-about and teaching-to. Nobody thinks telling kids about Henry VIII will turn them into wife murderers)

Also note how you've shifted from "please allow these other systems to operate" to "let us expose all children to these other systems".

Nothing has changed.