When considering whether to participate in the PGP, you should keep in mind that mistakes happen. The sequencing results, or the data that are posted on websites, could contain errors. The psychological impact of errors could be significant. If the project or some third party (possibly erroneously) claims that you have a predisposition to a debilitating disease, you shouldn't overreact. You should consult a physician or a licensed genetic counselor.

As a participant in the PGP, you could learn that you are at risk for getting a disease that has no cure or treatment options. How will this affect you psychologically? How will it affect your relatives? Should you tell your children, your siblings, your parents? Do you by any chance have an identical twin? What will you tell him or her? (If you have a living identical twin, by the way, the PGP requires that the twin provide consent for your participation in the project.)