ww - to my knowledge there were always castrato sopranos. In the early times of course one aspect was the difficulty to get female or boy sopranos into monasteries. But later when public performances were done there also was a time when (few) male sopranos really could be compared with (much more) female ones. And I also have heard rumours that up to today the vatican has some hidden castrati for their own purposes (musical of course!).
Also very interesting: A man using his 'broken' voice (falsetto?) can nearly sing soprano. I never heard a female soprano doing something comparable (should sound like a steam pipe). But I do hear both of them yodeling.