Then there is the matter of potential recrimination — from siblings, parents and children who share half of the participants’ genes and did not necessarily agree to display them in public. Prospective participants are advised to consult with first-degree relatives, but except for identical twins, their consent is not required. Some volunteers are worried about their hurting their teenagers’ dating prospects.

“A potential boyfriend could look at my genome and say, ‘I don’t know if this relationship is meant to be,’ ” said John Halamka, a participant and the chief information officer of Harvard Medical School, who has a 15-year-old daughter. (His daughter, he said, told him that if a suitor did that, “I wouldn’t want them as a boyfriend anyway.”)

Because of the known and unknown risks, Dr. Church required the first 10 participants to demonstrate the equivalent of a master’s degree in genetics. Most are either investors or executives in the biomedical industry, or else teach or write about it, so they may have a financial interest in encouraging people to part with their genetic privacy.

The project has drawn criticism from scientists and bioethicists who caution that even its highly educated volunteers cannot understand the practical and psychological risks of disclosing information long regarded as quintessentially private.

“I’m concerned that this could make it seem easy and cool to put your information out there when there is still a lot of stigma associated with certain genetic traits,” said Kathy Hudson, director of the Genetics and Public Policy Center at Johns Hopkins University. “There will be new uses of this data that people can’t anticipate — and they can’t do anything to get it back.”

For now, the PGP, which is privately funded, is sequencing only the fraction of participants’ genomes thought to have the most influence over disease, behavior and physical traits. But the question of how much value to place on genetic privacy has taken on more urgency as the technology for sequencing an entire human genome accelerated and the price has plummeted to as low as $5,000, so that it may soon be possible for everyone to possess their own genetic readout.