It does sound more genetic than anything else. I did try threading a couple times for my eyebrows, which I know is really different and I didn't think it any more or less painful than waxing, nor did it seem to last any longer and once they accidently ripped out half my eyelashes in one eye, so there's that....
On the other hand, I'm very blond and of Scandinavian descent, and have almost no body hair. I don't even have to wax my eyebrows more than a couple times a year, so it may be different for you.
Hope you find something that works.