to Machination:
I say go for it. You don't know when the affliction will strike or if it ever will. And if it does after you've had a fulfilling career as a practicing dentist, you can do other things just as fulfilling with your dental education and experience, like teach at a dental school.
If you are really worried about it, perhaps you might want to consult a physician about your father and grandmother's conditions and inquire about your risks of developing the same ailment, and if there are any proactive preventive measures you can take.
If you have the tremors now, then I'd really worry and debate whether or not dental school is a viable choice. But if you don't have any symptoms, live your life and enjoy it to your fullest while you can! Life is short. 🙂
(yeah, yeah, I know, I know. "Enjoyable" is not a really good description of dental school.) 😀