In this case, there are two varieties of horses: Domestic horses that are raised and bred by humans and Wild horses that lives in the wild. The issue of varieties in coat colour of domestic horses can be explained as what occured by selective breeding, also known as artificial selection which is a technique by which humans develop new offsprings with desirable and suitable characteristics. These breeders select two parents that possess beneficial phenotypic traits to mate, producing offsprings with those desired traits such as strength and also for coat colour as stated.
Believe it or not, in this case having a blood type different from either parent is by far the most common result. In most cases, an O parent and an AB parent will have only A or B kids.
