https://www.nature.com/articles/s41598-020-66232-1?fbclid=IwAR3Wm43WEfgun-Cf9TWEH8ThF8AGrXL1d0TdcoBgr7AxpbwStKZ7E1FjE-k
Also, contrary to popular belief, we could detect no significant genomic contribution of the Arabian breed to the Thoroughbred racehorse, including Y chromosome ancestry. However, we found strong evidence for recent interbreeding of Thoroughbreds with Arabians used for flat-racing competitions.
Finally, we identified undocumented relationships between the Thoroughbred breed and the modern Arabian that are contrary to breed registry regulations and dispute long-held myths. Although celebrated in many historical accounts20,36, the three “Arabian” sires recorded as the main male founders of the Thoroughbred breed (the “Darley Arabian”, “Godolphin Arabian” and “Byerley Turk”) were likely individuals of other Oriental horse populations, and the Arabian breed appears to have contributed little to the autosomal genomic content of the modern Thoroughbred (Fig. 3).