Science Questions the Value of Pedigrees

According to a research report out of the University of Edinburgh in Scotland, a racehorse’s lineage is far less significant than was previously thought. Instead, nurture is more important than nature when it comes to determining which horses will win.

Alistair Wilson, an evolutionary biologist who headed up the study that was published on Dec. 18 in the Royal Society journal Biology Letters, found that genes accounted for only 10 percent of the prize money a horse wins in its lifetime. The other 90 percent is determined by how a horse is trained and ridden.

Owners who stand top stallions can fetch thousands of dollars per breeding, but according to the research report, stud fees are not a good indicator of a horse’s quality.

The report analyzed lifetime earnings of more than 4,000 horses used for racing and breeding since 1922. The study revealed that while there are good genes to be bought, it does not appear that you get what you pay for. The offspring of expensive stallions might tend to win more money, but not necessarily because they have inherited the best genes. The research concluded that breeders who can afford to pay high stud fees are also able to spend more on horse care, including how the animal is trained and who rides it — all of which will contribute more to how much it will win.

Researchers found that there are situations where good genes are important: If every breeder spent a similar amount of money on the care of a horse through its life, then the difference between a winning or losing horse would come down to the details, such as the parents. In that situation, picking good parents could give a foal an edge.