I don't believe an accident of birth makes people sisters or brothers. It makes them siblings, gives them mutuality of parentage. Sisterhood and brotherhood is a condition people have to work at.
I love wisdom. And you can never be great at anything unless you love it. Not be in love with it, but love the thing, admire the thing. And it seems that if you love the thing, and you don't just want to possess it, it will find you.