Why would a culture require a puritanical religions to have an aversion to discussion of sex? And do you consider an aversion to discussion of sex to be default lacking or present in a population?
Because why else would such an aversion arise?
I don't think there are any sensible "defaults" for human cultures. But I wouldn't expect aversion to talking any sex to arise spontaneously among a population that hadn't had it imposed by prior generations or from outside. We're naturally curious beings and have lots of sex (compared to other species).
The default is humans are naked or mostly-naked and have sex in the same small dwelling where their children sleep. Everything from there has been downhill.