I wouldn’t say it had to be emotionally challenged, but definitely a little bit off in one way or another.
Intelligence of sorts runs in my family; My dad was a PhD EE who would have been labeled Asperger’s had that diagnosis existed, I was in a gifted program in elementary through high school, and my older daughter, when offered both a gifted program and an opportunity to go to 7th grade at age 9 declined (she said she was already the youngest kid in 5th grade AND had the oldest mother). The problem is, Dad was really smart, my daughter is really smart, my sister got the engineer gene too- and what I think fooled them all is that I have both an eidetic memory (at least short term) and reasonable intelligence.
I have in common a disdain for commercial sports, moderate impatience for those who can’t process things as quickly as I, and a lack of pleasurable response to psychoactive drugs (with the exception of caffeine and alcohol). My father didn’t see any point in them either 
and would say so, along with other socially rude things, at the drop of a hat.
It’s been a pleasure and an honor to have the acquaintance of a young man who started college at 14, had a JD at 19 (and got a job in a law firm to finance his medical school) and I believe finished his residency at 23. He got along well with everyone well socially, isn’t obviously nerdy, is married with three kids to another ER doc, and is also (!) a politician on a local level- state representative. Now HE is a genius. His mother told me he was the only college freshman who had to have a girlfriend drive him a round (he wasn’t old enough for a license).
I read a quote somewhere that (paraphrasing) the difference between true ‘genius’ and ‘just really smart’ is that with people who are just really smart, you feel like you could accomplish the same thing, if only you had a bit more discipline or were just a bit smarter at an earlier age.
OTOH, a ‘genius’ makes connections in such a way that most of us can’t even comprehend how his brain works.
Your friend sounds like the former. I’ve passed law and other college classes (BS engineering and MBA) and med school classes are just more material to learn. So it stands to reason that if I was smarter and more disciplined, I could maybe have done it faster like your friend.
The ‘genius’ is the guy who can come up with a workable theory for an artificial heart without ever having taken a class.
I was lucky in that when I went to high school it was large enough so that very smart kids got collected in extra honors classes. I had a reasonably good high school experience. Then I went to MIT. In both places there was a wide variety of emotional types, from typical nerd types to swingers with dates every weekend. I suspect a lot of the the stereotype comes from people thinking those who do not meet it as not quite as smart as those who do…