When Rags to Riches won the Belmont Stakes it marked the first time a brother-sister duo both captured a jewel of the Triple Crown.  Besides the fact that the odds of one mare throwing two Belmont Stakes winners is about the same as the odds of winning Powerball, the event underscored the importance of the female line when it comes to winning a leg of the triple crown.

There’s a tendency in racing to let data dictate the discussion rather than the other way around. This is the primary reason sires have been overvalued in pedigree analysis and broodmares have been undervalued. The dosage index, which I have commented on in an earlier piece, classifies only the male members in a horse’s pedigree. The problem with this is that stamina tends to run along the tail female line. This means that going forward it is important to research the female families of the derby contenders, but we must first understand how to properly do this.

Luckily for us all, bloodlines.net has some great diagrams on all of the female families. I looked through them and identified seven exceptional families whose descendants have had success in classics time and time again. This doesn’t mean that their descendants are a lock to win this year’s Kentucky Derby, it just means that you should pay closer attention to the Derby contenders who descend from these families. I have listed the family number, the famous descendants and a rating from one to ten, with ten being the highest, on how relevant I believe the family currently is.

With the gap between the great families and the less than great families getting wider each year, it will be interesting to see how this angle plays out in this year’s derby. I will not get into the descendants of these seven families as yet because it is too early, but I hope to discuss this angle in depth as the derby approaches.