My vote is no on yet another useless feature. Untill we get more important things fixed/added that so many people have begged and pleaded for that would actually benefit the game and everyone, then my vote is no.
Obviously it doesn't affect a horse if you breed back to the same stud and it's a good match. But several top KNN breeders just Svened their top girls to National Treasure and then his descendants (also Scp weak ) and hoped for the best. The current #1 KNN (weakest in Scp, has got to have Nate in there 30+ times.
I think it would be a fun stat to add. I assume most serious players won't let it change a horses worth so I don't imagine it will affect the game that much