Which child performs better, the first born or second? When I was a child, my parents worked on phonetics with me, and encouraged me to work with my sister on

Which child performs better, the first born or second? When I was a child, my parents worked on phonetics with me, and encouraged me to work with my sister on hers. She didn't perform as well academically as I did, but now that we're in our mid/late thirties, that discrepancy is nothing but a footnote.