The way I look at it is, if they wanted to get you, they will. I rather be concerned with learning about myself and potential health risks, than worry about something with a low probability of happening. You can have it deleted from their database as well afterwards.
Y'all right. If they want you, they want you... I'm being over the top.
Eat a well balanced diet (avoiding processed foods as much as possible), avoid stress, exercise and you'll be alright. Don't buy into the whole genetic health TOO much. If your family ate nothing but trash and developed heart issues it doesn't mean you have no hope, it just means you began life at a deficit because of their choices. Healthy choices should be priority even if you don't have these worries.
I don't buy the deleted thing because it may help with their future research, just like I don't buy that Google/Facebook get rid of all your information. But again, you guys have made me view it differently and I may end up doing the test, who knows.