Неяснотии при хибридизация:

[enarei]

http://www.akaradobe.net/hinnyfav.htm

...Donkeys have 31 pairs of chromosomes or 62 in total. Typically, mules and hinnys have 63 chromosomes, they inherit 31 chromosomes from the donkey (E. asinus) and 32 from the horse (E. caballus) (Trujillo). After reading several scientific articles I am not 100% convinced that all hybrids contain 63 chromosomes and maybe more research needs to be done. Most of the reports I have read in regards to hinnys and mules are the rare cases where both have produced offspring. Even more interesting one article found that an intact male hinny contained both horse and donkey sperm cells in regards to chromosome counts (i.e. some contained 62 chromosomes and others contained 64 but none contained 63 chromosomes) (Trujillo). The mystery continues!

Този въпрос всъщност не е толкова сложен за проучване от техническа гледна точка.