Is my hair gray or grey?

Merriam-Webster opines: "Gray and grey are both common spellings of the color between black and white. Gray is more frequent in American English, whereas grey is more common in British English. The varying usage of both grey and gray extends to specialized terms such as animal species (gray/grey whale) and scientific terms (gray/grey matter). Greyhound is an exception, which has a different derivation than the color. It derives from the Old English grǣg." I think I was told once that gray hair is actually white mixed with whatever it used to be.