||The standard for evaluating thoroughbreds in direct female descent, based initially on tracing every winner of the five English classic races back to the earliest recorded mares was developed in the late 19th century. It was popularized by Australian Bruce Lowe, and expanded by later researchers. As it turns out, geneticists have found that mitochondrial DNA, passed from mother to daughter, is a valid method of tracking population changes in all species, including thoroughbreds.
This section offers a brief history of the development of Female Family Numbers in the thoroughbred, and provides an overview of each identified female family, including charts of descent, illustrations, and descriptions of classic winners and notable horses in each family.
This section also includes lists of the Kentucky Thoroughbred Owner and Breeder Association's Broodmare of the Year, and of Canada's Sovereign Award winning broodmares.