The Simpsons

If he was 10 years old in the first episode, which was in 1988, he would be 32 years old this year.

Lisa would be 30 years old

Maggie would be (approx.) 22 years old.

Homer and Marge would be 56 years old (Assuming an age of 35 years old during first episode)

10

He’s ten. The characters say it more than once, once example being in the episode “Lisa’s Sax” where Bart tells Lisa, “You are eight, and I am ten. In my two extra years I’ve learned…”