10 - 13 year olds still look small and childish, while late teens (16 - 18) look like adults. Besides in the US, 16 year olds can get driver licenses.
Getting off topic here. Anyways, I just thought it was weird to see my dynasty children still babies after 50 years. Also I noticed their birth year keeps moving up year-by-year after a certain point. Ditto for sovereigns, spouses, and heroes. When I start the game, it says my sovereign birth date is 130-something AC. Then when the game is at 220 AC or whatever, the birth date becomes 170 AC or so, which is silly because I started playing in 159 AC like everyone else. That means my sovereign wasn't born yet?