Previously, On Arrested Development

11 episodes feature this joke:

Season 1

3: Bringing Up Buster

Buster was born 11 months after Lucille and George Sr. stopped having sex.
20: Whistler's Mother

Oscar mimics Buster, giving a backrub and saying, "Hey, nephew."

Related Joke: ... gives back rubs (foreshadowing)
21: Not Without My Daughter

Oscar mimics Buster and gives a back rub.

Related Joke: ... gives back rubs (foreshadowing)

1: The One Where Michael Leaves

Buster: "Then I'd look like you." Oscar: "More than you'll ever know."
2: The One Where They Build a House

Oscar: "I know where the boy came from."
3: ¡Amigos!

Lucille is not having an affair with Buster's "uncle."
4: Good Grief
11: Out on a Limb
16: Meat the Veals

Buster: "My father?" Oscar: "Yes?... I mean, yes."
18: Righteous Brothers

When Oscar burns himself on the Cornballer, he shouts "This is my father's fault!" to which Oscar replies, "My fault?!"

Sources: Joke data compiled by Adam Cole / NPR. Episode metadata from The TVDB via a Creative Commons Attribution 3.0 United States (CC BY 3.0 US) license.