nwykstra: In lore reasons stat the blond hair recessive gene is gone from the human race at this point.
That whole bit about Blonde Hair being recessive is from a poorly informed BBC article from 16 years ago, which was proto-fake-internet-news apparently, at the time.
Also, I'm pretty sure the lore, since the 80s, has had blondes. This argument keeps cropping up as defense from people who seem like they've never actually been exposed to Battletech before. Kinda odd. Granted I haven't delved into this game but have observed from a distance, just seems bizarre.
Seriously, go read the old books on the Wolf's Dragoons or others--the fiction and what-not. Blondes abound, Clanners and Inner Sphere alike, high-borns and average mech-jockeys and below. Honestly the Houses and their backgrounds were largely a patistiche/palette drawn from broad Western/.European, Indian, and Chinese/Japanese/Broadly Pacific Asian civilizations and the peoples within them were largely implied to reflect that, at least according to the compendium I have sitting on my shelf. Not like you had monolithic bodies of people but there was a fair bit of consistency among them, again, going off the ficiton. You could find pretty much anyone of "stereotypical" historical and cultural backgrounds, like all the other games FASA put out at the time. Kinda like how you could have a German netrunner working with a full-blooded Sioux warrior in Shadowrun, for example. Nobody was really left out--incidentally, including blondes.
Their explanation is inconsistent and nonsensical in the context, and seems driven by other factors, but I deign to suggest what that might be, because I really don't know.