Did they get bigger as you were "Growing up"? Then we grow teeth, you're just being pedantic about whether they're brand new or not.

It may be fun, but it's not a fact. At birth, you likely have all the tooth buds to grow your primary teeth and maybe your permanent molars. Premolar and canine buds typically form during the first year of life. Second molar buds form around age two. Third molar (wisdom teeth) buds don't begin developing until around age five to six and in some folks they don't grow at all.

I have a condition where my lower front permanent teeth never developed. We weren't sure if any of our kids would have the same issue so we discussed it with the dentist. They couldn't tell us if all the permanent teeth were present or developing because there hadn't been enough time for first xrays to show all of the permanent teeth buds growing. Even at age 3.

This is not true. I’ve seen x-rays of a child’s mouth with clearly no adult teeth visible below the gums. Later I’ve seen X-rays of the same mouth with one or two adult teeth below the gums where baby teeth are about to fall out. The adult teeth are there underneath once the baby teeth fall out but they are not there “from the start”. That isn’t even to mention the size problem.

so I used to think this (till this past week), it's not quite true. Yes, ther are images of showing child skulls with lots of teeth. those are generally hyperdontia.

A regular child skill looks more like this x-ray

https://ccdcsmiles.com/userfiles/651/images/IMG_4253.jpg (from a dental clinic I found while searching).

Yes, you can see the adult teeth, but not all of them, and not like the hyperdontia cases.