Simple things like
Selle Francais =registry, not a breed
Hanoverian =registry, not a breed
Holsteiner =registry, not a breed
AQHA, only a mid 20th century “breed” designation
And some science:
Excerpt: The horse in this case is probably not directly related to any of the three Warmblood breeds but is a mixed blood animal that has some Thoroughbred ancestors, which is what the DNA analysis shows. Do read the explanation of results at the above website. The lab fully admits that this testing does not always give a reliable result but as this case shows, it usually does give a reasonable one.
E. Gus Cothran, PhD
Professor Emeritus
Texas A&M University
College Station, Texas