Hinny sixty cases of foals born to female mules around the world have been documented. In contrast, according to the ADMS, there is only one known case of a female hinny doing so. Namely, in China, in 1981, a hinny mare proved fertile with a donkey sire. When the Chinese hinny was bred to a jack, she produced the so-called "Dragon Foal", which resembled a donkey with mule-like features. In Morocco, in 2002, a mule mare bred to a donkey sire produced a male foal. DNA testing revealed the foal has a mixed karyotype hybrid like the Chinese hinny offspring "Dragon
Domestication of the horse less than expected based on the overall genetic variation in the remaining genetic material. This indicates that a relatively few stallions were domesticated and that it is unlikely that many male offspring originating from unions between wild stallions and domestic mares were included in early domesticated breeding stock. Genes located in the mitochondrial DNA are passed on along the maternal line from the mother to her offspring. Multiple analyses of the mitochondrial DNA obtained from modern horses as well as from horse bones and teeth from archaeological and palaeological finds consistently shows an increased genetic diversity in the mitochondrial DNA