I don't have one, never really wanted one either, but we have a little sister in our house. She loves her big brother. She thinks she's 16. She thinks she can drive and do everything that no only Tate does but also Ryan and me. But she's sweet, loving, and caring. Now from the big brother's view, she asks a ton of questions, repeats everything, follows him around and tries to do everything he does. You have to love them anyway.
There are many different types of sibling relationships, I didn't have the typical, just a pair of double cousins (Matt and Andy Scasta) who lived 200 yards down the way, around the bend in the woods. They were at my house all the time, we had the swimming pool. And every Christmas Andy would ride down to see what I got. We would make cookies with his mom and they had the first showbarn for the cattle. I even remember Matt letting me ride one of his first steers from the barn to the house. Now we would never dream of doing that. I washed cattle in a swimsuit (hum, wonder why I work cattle in a swimsuit cover up now!) We all have siblings of a sort, people we grew up with, people we call siblings even though they aren't our blood kin. Love them anyway.