Your chances are actually pretty good but that is not based upon genetics but the apparent fact that PD often skips a generation or more even when familial.
A few years ago the percentage of PwP of genetic origin was considered to be about 8% but in the last year such institutions as the Mayo Clinic have revised their estimates. I've read both 15% and 20% as a recent guestimate but even the majority of those cases seem to need the environmental triggers of idiopathic PD.
There is also a school of thought in more than one research institution which feels that essentially all PD cases are genetic and that with rare exceptions, there is no idiopathic PD.
Conversely, PD appears in many ways to be a form of accelerated aging which. There are also schools of thought which are exploring the idea that PD is an inflammatory disease.
At any rate, maintain your caffeine intake from whatever source. If you smoke you might want to consider which is worse, lung cancer, heart disease or PD.
Read about the precursor symptoms. I don't mean the early symptoms which send you to the doctor for a diagnosis but the symptoms which appear to have no relationship to PD. Even a partial loss of sense of smell (you might notice that it affects your sense of taste because of the affiliation) depression, sleep issues, leg drag, change in handwriting, if you are a woman you might have prolonged pain in the neck or shoulders. None of these were ever seen to be related to PD but now they are considered symptoms which can begin years before the major loss of dopamine and norepinephrine neurons.
Of course, they could be just what they are, but with your family history, it is important for your doctors to be aware.
Consider that this is a good time to adjust your diet to a more Mediterranean style diet; to begin an exercise program the stresses not only strength (I'm a great believer in that because of the issues I have seen in some PD patients who don't) but range of motion, flexibility and balance. Yoga is a great form of exercise and so in aquatherapy. And dancing.
My husband has PD and I speak from both good and bad experience.