Edit: Screwed up title, mean to say "the average age of marriage"
I'm interested because a redditor elsewhere had claimed that
Men were expected to be in a gay relationship until they were about 30. Then they would marry a woman, get children and when the children were grown up they would be in a gay relationship again.
I have little to no knowledge of this topic, but this set of claims intuitively strike me as strange.
If society expected Roman men to marry at around 30, it seems strange for the consent ages to be so low. It also seems a pretty high age for the ancient world, I thought historically people generally married quite young. 30 seems old even now. And then there are all the famous Romans that come to mind who married young.
I know that pederasty was romanticized in (post)Hellenic Greece, but I don't know about Rome. I know that there were, depending on the time, strong socially conservative voices in Rome. It also seems a bit strange given the general impression of Rome vs. Greece that men would be expected to enter into a "gay" relationship, not merely that it was either socially approved/acknowledged/accepted- but that it was expected.
I'd also be quite curious to know how historians know about the practice of marriage and sexual attitudes of the common person in Rome (I imagine graffiti might be helpful?), and whether any of what the original redditor said was true in specific periods of Rome's history.
The redditor is on the track of something real with respect to men's marriage ages. There are many obscurities in the study of Roman demographics, but it's fairly obvious from both literary and epigraphic (tombstones, etc.) evidence that men tended to marry later than women did. Based especially on tombstone evidence, it is frequently proposed (e.g., by Scheidel at https://www.princeton.edu/~pswpc/pdfs/scheidel/110503.pdf ) that ordinary people married somewhat later than social elites (overrepresented in literary evidence) did, and into their 30s.
(A cautionary observation in the conclusion of the same article is that "the demographic parameters of ‘Roman’ marriage, in the broadest sense of the term, remain exceedingly poorly known.")
I would not put much weight on the idea that men are specifically supposed to wait until about 30 for marriage. For one thing, this needs to be narrowed down by period. In the early/mid Empire there was actually legal pressure to marry earlier than that (a man who still wasn't married by 25 faced various penalties under the Augustan marriage laws). Before the imposition of these laws, elite men of the Late Republic such as Pompey the Great (about age 20 at first of five marriages), Cato the Younger (~22) and Caesar (~17) often don't obey any "about 30" rule, although there are examples of men whose first marriage might fairly be said to be about 30, e.g., Cicero (~27), Sulla (~28), Clodius (~30, though this may have been a second marriage). It's fair to say that it was common to marry late, even as late as the 30s, but not that there was an expectation to wait until 30. The bell curve of men's marriage ages likely has its center in the late 20s or around 30 (with plenty of room for earlier), and it might be fairer to imagine 30 as the age when an eligible man might start to be seriously leaned on if he still hadn't married.
With respect to homosexuality, this is not on the track of something real. The level of tolerance and/or opprobrium that ancient Roman society attached to (male) homosexual acts varied based on who the actors were and which of them was doing what (and on when we're talking about, of course), but in no Roman period were male citizens expected to alternate periods of formal homosexuality and formal heterosexuality.