No, I don't have friends. I don't want friends. Steven is...

Steven.

Family, to my understanding, is a factor unique to Earth-based lifeforms, in which their genetic benefactors take responsibility "raising" their spawn, also known as a "child," from it's most useless state until it is suitably more functional. With this additional functionality, while it loses "cuteness" it instead gains "knowledge."

[ She's... rather proud of her understanding. ]

So you are saying a "brother" and "sister" are words for when there are multiple spawn involved, and that is the word for their relationship to each other.