Grey dam doesn't guarantee a grey foal. Grey is dominant, but mare may be heterozygous for grey and have passed on a "normal" colour gene.
Im still not sure that filly is grey, looks like a shade of brown Posted via Mobile Device
The greying process can take awhile. My coming 2 year old is just now really starting to get a substantial amount of grey under his winter woolies, if you saw him from a distance he looks bay. Same with my weanling filly. I know they are both grey, dam is homozygous.