To increase the chances of breeding an elite racehorse, a genetic dominance tree (GDT) of the prospective dam, and a GDT of the prospective sire, are constructed. A GDT has indicia for determining whether the horse has any dominant and substantially constant representative physical characteristic in the form of a combined body length (CBL) in its family. The prospective sire and dam are bred where there is such a dominant and relatively constant CBL common to both horses.
