The ages were probably easier to "remember" than their names: they're all at two-year intervals except the 18 / 15 / 12 stretch in the middle. My father often confused my and my sister's names even though we were the only children in the family. A near-genius who couldn't figure out some of the simplest things.
From the Orioles' White Album:
Oh, show me round your dusty diamonds way down south,
Take me to the Norfolk farm.
Let me hear Pat Valaika's striking out,
Come and keep his benchmates warm.
We're back in the AAAA!
We've got no one to pla-ay:
Down in the Double-, down in the Triple-
Down in the AAAA!