I guess i’m one of the lucky ones. I can do one or two one armed pullups right now but I don’t really train them. I wouldn’t be able to train one arm very well yet and given that I only have the opportunity to do pullups in a gym with dumbells limited to 70s I can’t train my pullups effectively, I can do too many for effective training with a 70 on my feet and i haven’t found a way to use a barbell in that fashion.
I do think it is probably genetics to do with this from my high school observations. I get to see how people are naturally built before they start to train, and that’s usually a pretty good indication of what their strong point will be once they do. Personally I started out with really strong biceps and lats for the rest of my size, and also very small legs. I am 5’10" 145 now by the way. I am gaining weight rapidly thanks to milk so lets see if I can keep the pullups up to snuff as I do!