I remember a few years ago when this topic was in hot debate, we started to worry about whether insurance companies would refuse to insure someone because of a genetic predisposition.
Now the debate is on whether you would like to know if you have the genes for say, colon cancer early. Would I choose to fall in love, marry, have children, buy a home, etc if I knew I couldn't see it all through, that some genetic mutation was going to keep me from living happily ever after?
And does this keep the earlier fears from again rearing their ugly heads and because of this information, we are refused health insurance, or life insurance, or a mortgage, or car insurance.
If the medical community could guarantee me a cure and the government could guarantee me that I could get insurance and such, then maybe. BUT If having this genetic defect was going to impact my life then no, I wouldn't want to know, I'd like to stay unaware and happy and deal with the disease when/if I had to.