I don't think a DNA test will tell you what colour he is? To me he looks brown/chocolate, so similar to the "sepia" and "mink" ragdolls (which to me is just different ways of saying varying shades of brown, same way someone might call a light red cat cream). Solid brown cats are pretty uncommon, and the kittens tend to darken to a black as they age, though some keep their distinct brown coloration, only time will tell!
As far as cat genetics if your interested I'll try and recall some of the information I remember looking up in the past, wish I could remember the source I got it from because it was excellent, and I'm probably remembering some things incorrectly, but here we go:
As far as I can remember, cats can be one of two colours: red or blue. All the other colours are some sort of varying shade of a red or blue. So a cream coloured cat is generally a dilute red, while a lilac cat would be a diluted blue cat. So technically speaking I think brown cats are just a different shade of "red" as it were, but I'm not entirely sure, since people are able to breed true for brown (Havana Brown cats) without having other shades pop up, so maybe it's some sort of recessive shade. Any one of these colours can have varying levels of white spotting, which will result in tuxedos, the van pattern and any other level of white imaginable. Cats who are all white (not pointed) still have some sort of underlying colour, but the white spotting gene covers their entire body, instead of only a portion. So those white cats may have the gene to code for red or blue, but none of that is showing, because they are completely covered by white spotting.
That was probably a little more than you were looking for, but it was a good bit of procrastination for me
not even entirely sure I got it all right