My first little brother is a veritable storehouse of seemingly useless information, that is, until you want to buy a car, or a boat, or a motorcycle and then you'd better believe he will get you the very best for your money.
My second little brother has taken enough high-level math classes to give any of us a headache.
My only little sister is spectacularly creative and has quite the quick wit (developed in part with help from the first little brother.)
And me? Well. As I am the oldest sister, naturally, I taught them everything they know. Except random facts about energy efficient vehicles. Or linear algebra. Or how to paint a lovely canvas of a water-skiing brother.
As much as I would like to gloat I am sure this isn't true of our family.