This seems to me to indicate that there might be some genetic factors involved in dappling, although they are undetermined at this time. It has also been said dappling indicates a state of good condition or good nutrition. It may well be that good nutrition has an influence in the expression of dappling. However, it doesn't explain why dappling seems to run in some families and not in others, and why dappling shows seasonal and yearly variations in horses that are well fed and in a constant state of good nutrition. Gremmel and Zublin's research did reveal some interesting things about dappling.
Dapples seem to be centers of networks of capillary arteries.
The degree of pigmentation depends on the blood supply, but there is no connection with layers of fat under the skin. The skin under a dapple appears less pigmented than the surrounding areas. The hairs in the center of the dapples are shorter than those on the outside hairs surrounding the dapple. Thus, I feel that there might also be some sort of genetic control for Dappling as well.