Yep its genetics. I hunted a different county in Ky a few years ago than I do today and a high percentage of bucks on that farm had no brow tines.
I have lived and hunted here since 1987 ... And have seen very few with out any brow tines over the years ... If it is solely genetics .. It must be a recessive trait ..? I have a good friend that was making his own trail cams long before they became tools of the trade .. He studies his herd year after year ... He told me that he has never seen a buck possess the "no brow time" trait it's whole life ... Has any other "deer watchers" noticed this ??
That's actually pretty cool he's got no brows, I would make sure he makes it the next two years than put him down!
I'd guess just a young deer that didn't grow brow tines this year and probably will in the future. If he was three or older then I'd say its genetics, but he's far from reaching his genetic potential.