Ditto’s on “Late-Talking Children”. One of our kids barely said a dozen words for the first three years of his life - we were kinda concerned, but were reassured by the fact that by the time he was two, it was clear he understood pretty much everything we said to him (and most of what we said to each other).
I had heard of Sowell’s book, so my wife and I read it - the situation Sowell described for his son very much paralleled what we saw in ours. Sowell’s message was pretty much if your kid seems normal in every other way, don’t panic.
And sure enough, shortly after our son turned three (and just before he started pre-school) he started talking like any other kid that age, and pretty soon you couldn’t shut him up. As he grew up, you couldn’t ask for a better, smarter or more articulate kid.
Maybe he just didn’t see any point in talking until he had something to say (not that we all couldn’t use more of that).
I had a friend (male) who told me he didn’t talk until he was 6...but he also had 5 or 6 older siblings...said he didn’t need to talk!