(Source: ~25 years experience working with horses as a hobby) At least in the US, inbreeding is indeed extensive. The vast majority of male horses are castrate

(Source: ~25 years experience working with horses as a hobby) At least in the US, inbreeding is indeed extensive. The vast majority of male horses are castrated at a young age, since intact males are considered more difficult to train and control (therefore more dangerous to humans) and more expensive to house than castrated males or intact females. Therefore, a small percentage of males end up fathering all the offspring. There are American Quarter Horse stallions with literally thousands of offspring (sometimes to their detriment, as when a popular stallion was belatedly discovered to carry a recessive genetic disease[0]). It's therefore interesting to a modern horse person to read that "the Scythians maintained the natural herd structure" (a "harem" structure in which one male tends to sexually dominate several females - but several, not thousands, and not generally for his entire life). [0] https://en.wikipedia.org/wiki/Impressive_(horse) https://en.wikipedia.org/wiki/Impressive_(horse)