This is genetically next to impossible, anyone with an elementary knowledge of DNA and chromosomes should know that. Horses have 32 pairs of chromosomes, humans have 23 pairs, the two cannot interbreed.
Humans are of the genus "Homo" while horses are of the genus "Equus", totally different even if one is to entertain the extremely rare intergeneric crossbreeding.
I mean even their families are different, with humans being from Hominidae and horses from "Equidae".
The only thing they have in common is the class Mammalia which is so high up the food chain to make it practically impossible to crosbreed. There are no known interordinal crossbreeding (breeding between different orders).
Labda ungesema binadamu azae na nyani.
Biology ya form one tu inatosha kujua yote haya.