I've never played Pathfinder 2e, but I've played both the 1e tabletop and Kingmaker. Is any of that a potential problem?
I was thinking it might be worth rolling a sorcerer whose powers betray an ancestry he'd rather not think about, and who got chased out of his village as a changeling despite (to the best of anyone's knowledge) having actually been born the usual way in the village. (He'd naturally be a bit nervous about showing off anything that could only have come from his weird ancestry, but I figure he wouldn't have signed up for this party if he thought he had to hide his sorcery entirely, and it's not like showing off that he's a sorcerer would automatically raise red flags.)
As far as his mechanical ancestry (what most games call race) I was thinking he'd be human; I was thinking his sorcery would be the only hint that there was anything else to see here.
(I haven't decided exactly what that something else would be. I think I'd look for something he has a real reason to hide.)