Humans are a bit different than horses. It has been well demonstrated and documented that first born humans are far superior in both physical and mental attributes to their lesser siblings...and if it were not so, I would draw upon my first born intellect and abilities to make it so...
I'm the 3rd child. The first has a different mom but same father, the second has the same mom and dad as I. The first one was a model with success in the fashion industry, the second one is a genius but socially awkward, and the third is compassionate, doesn't take **** from anybody, really nice, and amazing with people and animals.
I say I won out :P
Jokes aside, all offspring have their faults and their winning qualities.