do older siblings often make friends with older siblings and vice versa?

[littlebylittle]

dd, 4 is at pre school and is outside a little gang of friends that she would like to play with. I am very open to encouraging friendships and don't want to push friendships that aren't flourishing, but there seems to be a little pattern which I want to know if it bears out . all the little group are younger siblings and the people dd seems to get on better with are older siblings. Is this a pattern that anyone else has noticed or is it just me?

All of dd1's friend, bar one, are only children. The other one is a youngest. Her siblings are much older.

Dd1 is an oldest. There is four years between her and dd2. Her friends all like to make a fuss of dd2.

One even made up a little sister. But her mum left her in Tescos so she went to live with the woman over the road and now they don't know where she is