>>>> Question though. If you look back, you see a sire; Sonny Dee Bar; is registered as a QUARTERHORSE, as is the dam he mated with, Nicky Bar McQue. So how did two QH's produce Super Son Dee, a PAINT? It happens again with Thistle Sox Jr. And Barber Rose. How is this possible?
The Quarter Horse gene pool has sabino(s), splash, and frame overo in it. These genes, when their white-producing tendencies are more highly expressed, create white leg, face and body markings that have been loosely classified as "overo" markings. (Now that we know more about them, we know they are severalseperate genes, but early on, they were all lumped together as they created similar phenotypes, especially at their lower levels of expression.)
When AQHA was founded in the early 1940's, and for many decades thereafter, horses that had white past certain limits could not be AQHA-registered. The two predecessor registries that merged to form APHA in the 1960's, the American Paint Stock Horse assoc. And the American Paint QH assoc., were formed as a place to register paint-marked stock type horses including these "cropout" paint-marked horses from QH parentage. (Some would argue that the APQHA formed specifically for this purpose-- hence the name-- and the APSHA had this as a primary purpose as well.)
The Paint horses in your mare's pedigree that came from 2 AQHA parents were part of this era-- they qualified by color and by bloodlines, since until around 2004, APHA accepted any combination of registered Paint, AQHA, or Thoroughbred breeding for parentage of color-qualified horses. There were also some horses maintained both AQHA and APHA registration, since AQHA allowed a little morer white than APHA's minimum, so some registered QHs thereby qualified for both APHA and AQHA.
IIRC, it was in 2004 that AQHA rescinded its registration ban on those "too much" white horses, and began to register any offspring of two registered AQHA parents. (They left a show restriction on these excessive white horses-- their papers are noted and they can't be shown in a halter class.)
Soon after, APHA enacted a rule requiring all applicant horses for APHA registration had one registered Paint parent. This would stop registration of "new" cropouts-- but it does not stop AQHA x AQHA registered horses from being registered paint, as long as one of the AQHA parents also has APHA papers, which a fair number did, and still do.