I think that your sister's hair probably felt bristly because it was all sliced to the same length. That's the idea, anyway.
Anyhoo, I still can't really bring myself to shave my chin. I don't feel like it's necessary with the few hairs I have (if I shaved, I'd be shaving all my fine blond hair, which I don't want to do).
If this is hormone-driven ; couldn't I just take hormones of some sort? Isn't that the easiest way? Otherwise, I can still pluck (or even shave), it's just a PITA :P