Well, this is the way I was thinking of it, I don't know if you are thinking along different terms.
Ok, let's take 'Friends', and I am talking about for small children, learning about adult relationships, not teenager. The stories are laid out very simply, like a kid's reading book in school, not complicated, peppered with laughs to keep the kid's interested, but they also have their serious moments with the interpersonal relationship drama. So a kid can learn about the existence of things like gay people, infidelity, divorce, falling in love, losing your job, falling out with your friends, not knowing your mother/father, being adopted....they get the basics done in a serious manner, and will pay attention as they are entertained by the humour throughout the show.
'Friends' is probably a better example than 'Seinfeld' actually.