I went through the ThoroGraph sire stats from about 500 different horses recently and culled out the TGI and win percentages of each sire's male and female offspring separately.

As you might expect, the differences varied widely with the average being that a male offspring's TGI is better than the females by almost 3 full points.

However, about 10% of the sires show their daughters with equal or higher TGIs than their sons. While some can be discounted because there weren't enough offspring to make it too significant, but the vast majority are from active sires.

Anyone have strong theories about these sires with stronger daughters? I've read a lot about the X-factor issue recently and wonder if I'm seeing evidence of that (since sires can't pass the gene to sons, only to daughters) through these numbers?

Thanks, Mark



Mark Nickolas