You would see at birth if a foal was to grey.They will have white hairs around their eyes and at least 1 grey eyelash.To get grey one parent has to be grey.It cannot jump generations ,it has to be passed directly from parent to offspring.So no grey parent you will not and cannot get a grey foal.
Greys will lighten with age,a roan does not even though I have seen some wicked colour coat changes with the pony above ,her head will always remain dark and she will not eventually go white like most greys do.
This year she looks like a chestnut with a white spotty bum and is much darker than this photo.You wouldnt think its the same pony!lol
This is one of my arab foals an hour after birth.
You can see the grey "goggles" around the eyes ,indicating she will grey.

And now as a rising 3 yr old,she's definitely grey!lol.
