I know Jan was curious about if the Seinfeld gang were only children.

1. George - Even though he turned out to be an only child in later episodes, in earlier eps, he did mention that he had a brother.

2. Kramer - An only child(Kramer definitely broke the mold after he was born.)

3. Jerry - An only child.

4. Elaine - Elaine did mention that she had a sister, although we never saw her.

Thanks Brian. I'm surprised a sibling or two didn't make an appearance on the show. It would have been interesting. Elaine's sister and Jerry having a fling...George's brother even more annoying than George if that's even possible...the possibilities are endless.
I guess they had their reasons.

Wait Jerry mentioned having a sister in "The Chinese Resturant" episode, when he was talking in a rant about the ramification of ditching a dinner date with his uncle.

You're absolutely right about that.

Wait Jerry mentioned having a sister in "The Chinese Resturant" episode, when he was talking in a rant about the ramification of ditching a dinner date with his uncle.

The girl who played one of George's girl friends, who supposedly looked like Jerry, would have been great playing that part.

:)