The grey horse color includes a wide range of different types of grey horses. These range from a completely white coat color through to a dark, steely grey. But why do some horses turn a grey color?
The coat color of horses occurs because of their genetic makeup. Each horse inherits genes from its parents; these genes are paired, and the horse gets one of each pair from each parent.
So, as we have learned, the gene that causes a grey horse color is very dominant and will overrule all other color genes. However, most horses are not born grey and will turn grey gradually over a number of years.