>>33316557
>Traditionally boys and girls would be wed and bred by 15.
This isn't historically accurate for most times and places. In times/regions where good quality food wasn't readily available for everyone, girls would get their periods a lot later than they do today and would only get married after. For big families, the incentive to keep a girl in the house longer and have a free live-in babysit was much bigger than to let her marry the first guy who ever showed interest.

In the past men would explicitly be encouraged even in some societies to live out their sexual urges with hookers so they could marry rationally and not wed the first girl they liked. Got this from Stefan Zweig's "World of Yesterday".

You are right that just how long a child is typically living at home and how much control a parent has over the private life of a child they don't live with, is relatively recent. But the parental urge to have their kids focus on sensible pursuits rather than sex and infatuation has been around for a long time.