Mountain said half of 23andMe's customer base is searching for medical information, while the other half is interested in family history. What's more, of the 700,000 members it has today, 23andMe estimates that between 2.5 and 5 percent are adoptees looking for family. That's up to 35,000 people. The other 665,000 (and growing) who use the site may not have realized they have close relatives searching for them.

The trouble is that there's one key difference between 23andMe and other direct-to-consumer DNA tests: the other sites are explicitly family ancestry and genealogy sites. People sign up looking for relatives. 23andMe, however, was — until the FDA marketing freeze — the only company that bundles health, ancestry, and genealogy services. It's still associated with health information, and the company is seeking FDA approval to get its health interpretations back online. (Until then, users can download raw data from their genetic test and bring them to a doctor or upload them to a different site for analysis, if they choose.)

"We are the only service that had warnings," Mountain explained. "With the other companies you're automatically opted in." She said that 23andMe is "very explicit" about cautioning customers that they may uncover upsetting information. While the opt-in question will be removed, she said, the language in their terms of service is clear. It states: "You may learn information about yourself that you do not anticipate. This information may evoke strong emotions and has the potential to alter your life and worldview."

When asked whether 23andMe would be doing anything else to protect people from these revelations or to support those who do end up embarking on reunion journeys, Mountain said the company was already doing more than other direct-to-consumer DNA services, such as Family Tree DNA.

Joanna Mountain, the senior director of research at 23andMe, told Vox that the company was responding to customer demand: members were upset that their kin weren't showing up as family because they forgot join the program. "We had many more customers complaining about that than discovering someone wasn't related to them," she said.

Before Pearl and Schwartzman found each other, they had to consent to allow 23andMe to reveal close DNA relatives — by clicking "yes" on a message that asked them if they wanted to find their closest relationships. But as of September 12, 2014, new customers will automatically be opted into the service. (Existing members will be made aware of the change and given a chance to opt out.) This means anyone who signs up for 23andMe could now make an accidental discovery with no warning at all. [ UPDATE: After reading this article, 23andMe CEO Anne Wojcicki decided not to implement this change. The company is also planning to hire a Chief Privacy Officer. Read more about the policy reversal here .]

"My mother used to say, 'Be careful what you wish for.' [With 23andMe,] you can't know what you're going to find. It isn't all good stuff. It's not all happy stuff. And maybe some secrets are better left secrets."

The thought of finding a sibling never crossed her mind when she joined 23andMe. "You get this information online with no preparation, no support, no referrals, and no references that you might have if you were going to an agency to help you find your adoptive family," she said. She thinks genetic testing companies have an ethical obligation to offer information to people in situations like hers.

"I suddenly had to rewrite my own family history, which is a shock," Pearl said. "It did not make sense in terms of all the stories I had grown up with, in terms of what my life was. It did not include [my mother] getting pregnant, having a kid, giving it up for adoption."

At first, it was "fantasy land," Pearl said. "I found a brother. On his part, he found his biological family." She was happy for Schwartzman, for his relief. "I felt an immediate kinship and connection with him," she said. "We look similar. We have similar movements."

That's when she discovered Schwartzman. And her life changed. Afraid to ask her mother about him, she went instead to her mother's best friend for answers. The friend confirmed that Schwartzman was probably the son Pearl's mom had given up years ago.

While 23andMe warned her that the information she might find could be upsetting, she didn't think twice about it. She had no reason to. "It was innocuous. Not a big disclaimer," she says now. "It doesn't really prepare one for the potential news."

On her birthday in May 2011, she was sitting at her computer in her house, taking some time out for herself. "I decided to explore the [23andMe] website a little more. There is this little message that pops up and says — ‘want to find your closest relative?' I say ‘yes.' Why not?"

When she signed up for 23andMe, it was with the intent of exploring her ancestry. She had always been interested in her roots, and thought DNA testing could supplement her research. "I wasn't looking for anybody in particular," she said.

That kind of painful awakening is what Jolie Pearl says she experienced after meeting Schwartzman. When the excitement of finding a brother she didn't know she had wore off, she was left with more questions than answers and some bitterness about an experience she didn't feel she was prepared for or adequately cautioned about.

What 23andMe doesn't promote, however, is that these answers can sometimes be painful, especially when users aren't looking for them in the first place. The company estimates that so far 7,000 users have discovered that their parents weren't who they thought they were, or that they they had siblings they never knew existed. (The company uses the rather clinical phrase "non-paternity event" to describe these revelations.) As the site grows, there will be more and more family reunions, many of them by users who have no idea they are coming and aren't prepared for them. That's a lot of people potentially discovering truths and lies about themselves and their families.

Right now, 23andMe is back to negotiations with FDA, seeking approval for its health service and arming itself with lobbyists in the process . In the meantime, 23andMe has ramped up marketing for its ancestry and genealogy services. "Find out what your DNA says about you and your family," it promises. "Bring your ancestry to life." Through its relative finder program — a service launched in 2011 to allow people to see 23andMe members who share large swaths of DNA — people can contact "relatives across continents or across the street" from "close family to distant cousins."

That letter was quickly followed by a class-action suit involving claimants who allege 23andMe misled them by continuing to promote health promises — about helping people diagnose diseases or make better decisions about their medications — without regulatory approval and good science behind them. The complaint notice cited FDA concerns about potentially inaccurate and incomplete risk assessments for diseases and drug responses, which could lead users to make harmful or fatal choices.

Those health-related aspirations have also troubled federal regulators. In a sternly worded November 2013 letter , the Food and Drug Administration ordered 23andMe to stop marketing health interpretations for its personal genetic testing service until the company produced evidence for the claims it was making. Prior to the letter, the two parties had met face-to-face 14 times and exchanged dozens of emails, leaving the FDA to conclude that "even after these many interactions with 23andMe, we still do not have any assurance that the firm has analytically or clinically validated the [personal genome service] for its intended uses."

Founded in 2006 by Linda Avey, Paul Cusenza, and Anne Wojcicki, 23andMe's mission is to become the "world's trusted source of personal genetic information." Behind that mission is a reported $126 million in financing and these three goals: to " empower " people with information about their genetic makeup; to establish a massive database of human genes; and, Wojcicki claims, to revolutionize health care in the process. If people are armed with data about their genomes, the understanding goes, they can make personalized decisions about their health. That global DNA database can also change our understanding about the genetic causes of disease, Wojcicki often says. To figure out how, 23andMe has received $1.4 million in funding from the National Institutes of Health.

According to 23andMe, the story ends with brother and sister saying they were grateful to the service. Personal DNA science solved a mystery that state records or detectives might have in the past.

At the time, Schwartzman and Pearl were the poster children for 23andMe's "DNA relatives" program. Their story — and a picture of them staring at each other at a fork in a railway track — is still featured on the company web page about adoptees. They were, it seemed, among the many now finding family and having joyful reunions as a result of personal genetic testing. "It was the start of a relationship," 23andMe writes of Schwartzman's discovery. Then, Schwartzman hailed 23andMe as "an example of the miracle of modern science." Pearl called the reunion "the best thing."

The reunion went well enough that the family met again, once in California and once in Montreal. "It was nice to finally share this commonality with the rest of the world," Schwartzman said. "It was very emotionally satisfying."

His mother, who was already confused with dementia, gave Schwartzman a book, "a random gift she pulled up at last minute," he said. "It certainly wasn't a typical reunion you see on TV, where the music swells up and everyone is carried away on gossamer wings." Still, he said, "It was the welcome completion of a quest I had had for 50 years. It confirmed that I wasn't placed on the earth by aliens, that I had a mother."

Within a few weeks, he flew to California to meet his older sister, Jolie Pearl. They had their first meeting in a crowded restaurant in San Francisco's theater district. They were the first ones at the restaurant, and they talked until the place closed. During that same visit, on an emotional day he will never forget, he was reunited with his biological mother in Oakland, California. On the way there, he asked his sister what kind of flower his mom would like. They decided on a potted orchid.

Because of this "technological magic," as Schwartzman put it, he was reunited with his family with more ease than any other search he had undertaken. He was able to fulfill that deep, universal longing we all have to understand our origins.

The 23andMe website prompted him with a question about whether he wanted to find out more about the nature of their DNA relationship. He consented. Soon, he said, "We began to realize that my mother had a baby that she never disclosed to anyone." That baby was Schwartzman. "The whole thing was swept under the rug until — fast forward 50, 51 years ahead — and there I am."

In early May 2011, several years after enrolling, he was pleasantly surprised: an email arrived from another anonymous 23andMe user saying she thought Schwartzman might be a half-brother.

Unlike previous inquiries about his origins, this one occurred at the molecular level. He spit in a tube and sent it off to 23andMe's California headquarters for analysis. For about $100, they sent back information about his genealogy (biological relatives), ancestry (lineage and geographic origins), and — this was before a 2013 Food and Drug Administration crackdown — his health, including genetic predispositions for various diseases and behavioral traits. Schwartzman said he didn't expect much from his foray into personal DNA testing. He just signed up "as a last-ditch effort to try to get some medical information for myself."

All his life, Neil Schwartzman searched for his biological family. He was adopted in 1960 at 10 days old, and he never knew where he came from. At first, he looked for answers by going to social services in his hometown of Montreal, Quebec, and trying to access adoption records. "There was nothing in the file," he said. "Everything I did ended up being a dead end." As he approached middle age, in 2008, he had just about given up. That's when he heard about the direct-to-consumer genetic testing service 23andMe.

Sheila Jasanoff, a professor of science and technology studies at Harvard University's Kennedy School of Government, thinks that people are surprised by the family secrets they find in their DNA in part because they are not appropriately cautioned about what they're getting into.

"23andMe wants you to imagine their service is individualized: you send your saliva in, they send you your health risks, and you may find out things about yourself you didn't want to know. They want it to be contractual between you and them."

In reality, of course, DNA isn't yours alone. It contains information about your parents, siblings, and extended family, going backward and forward. Every time you put your DNA on one of these databases, you're also implicating all of your relatives for as long as these databases exist, whether they like it or not.

"Richard III's skeletal remains can be validated against DNA from living relatives today," Jasanoff said. "DNA can yield information about risks that may not be yours alone but also affect relatives, from breast cancer to schizophrenia. And, of course, it can reveal that you are not genetically related to people you regarded as family, as well as find family you never suspected you had."

Since the 1980s, the early days of genetic testing, these ethical and legal questions about DNA ownership remain largely unresolved. Tim Caulfield, a health law professor at the University of Alberta, said the story of Henrietta Lacks — a woman whose cervical-cancer cells started the first "immortal" human-cell line for research, unbeknownst to her and for a long time her family — might offer some guidance.

Last year, scientists sequenced the HeLa genome without her family's knowledge, which raised privacy concerns for Lacks' relatives. After negotiations between the family and the NIH, they resolved the issue by saying that the HeLa genome data would be made available through a restricted-access system. Though a committee that handles requests, Caulfield said, "Lacks' relatives have to be consulted in any kind of interaction with or research on the HeLa gemone." For now, though, there is no legal precedent to support the generalization of her case to others.

If Jasanoff could re-write 23andMe's alert system, she said she'd include some version of: "You will find out information about yourself, but keep in mind, it's not just about you: it relates to your family. You may find out you have a disease propensity and you will have to decide whether to tell your children and siblings. You may find out that you have relationships you did not know about."

Now that the health service at 23andMe is on hold, the company will be focusing even more on building up its ancestry and genealogy features. Unlike its medical offerings, the science behind these roots-related services is well validated, and — for close relatives — extremely predictive and accurate.

23andMe's Mountain is excited about the possibilities. "I love to hear those stories where people can learn something new through their DNA," she said. "I'm excited to continue to do that, that people can make discoveries through this hidden part of themselves they never explored before."

One of the driving forces behind 23andMe's switch to an opt-out system for the discovery of close relatives is CeCe Moore, a genetic genealogist from San Clemente, California, who's an advisor to the company. She is what's known as an "adoption search angel," helping people find their biological parents using online DNA testing.

We met at a genetic genealogy conference just outside of Washington, DC. When I walked into the conference center — a 4H Club in the middle of a tree-lined residential zone — a folksy gaggle of DNA enthusiasts greeted me at the door. Many had gray or white hair and seemed to know each other. One man, who was registering conference-goers, asked me to write about the regulatory clampdowns on direct-to-consumer testing and how backward and unfair they are to consumers who just want information about themselves. In other words, it seemed there weren't many critics present.

Moore could be the head cheerleader. Though she had to give several talks over the conference weekend, she said she had been up all night, guiding a "foundling" — a woman who was given up at birth without any record of adoption — through piecing together her family tree. "She got a predicted first cousin match on Family Tree DNA and I think it's her half-aunt," said Moore. So instead of sleeping, Moore combed her matches on other online genetic databases, including 23andMe, for information. She filled in the blanks of the woman's family tree through online searches of obituaries, Census data, and even Facebook.

For this obsessive skill and success at matching adoptees to their family members, Moore has gained some renown. She started out as a genealogy hobbyist just a few years ago and soon discovered there was a need for people who were good at building family trees to help others reconstruct theirs. Now, she said, as more and more people submit their genetic information to direct-to-consumer testing companies, "we are finding these stories every day. Every single day." She's also hearing more about those unexpected discoveries, like the one Jolie Pearl had.

Moore has taken to warning people about what they're getting into when they put their DNA online. "You will never find a bigger proponent for testing as me," she said. "However, I have come to the point that I do warn people that if they would not be able to emotionally handle discovering that their family is more complex than they think, they shouldn't test."

Still, she said that all the reunions she's experienced have been happy ones: success stories about families reunited far outweigh the traumatic ones, from her point of view, though she admitted she usually doesn't track the cases after their initial contact.

"It can be a roller coaster of highs and lows any time someone finds a close family member they didn't know about," Moore said. "But everyone I have worked with so far has said they are glad they know the truth."

When I first asked her about 23andMe's switch to fewer warnings for consumers, she said, like Mountain, that she was hearing from people who were distressed that they weren't seeing their family members match on 23andMe — and rarely the opposite.

As we said goodbye in the conference hall, Moore told me she also pushed for the change at 23andMe because it would make the work of search angels easier; she and others could help even more adoptees find their roots. All the people who forgot to click on that close-relatives option at 23andMe had been wasted to their mission, lost matches that could never be identified.

"There is no genetic privacy anymore, anyways," she smiled. This is a world where we volunteer our personal information and photos on social media, spill our hearts and pictures of our naked selves in emails and texts, and now even put the most granular information about ourselves (our DNA) on online databases like 23andMe. Search angels like Moore are there to fit the puzzle pieces together.

It's not the responsibility of companies like 23andMe to advise people about this, Moore added: consumers need to inform themselves about what they're signing up for. She said, "It's buyer beware."

As personal genome technology moves ahead at a breakneck pace, even the most informed consumers can be caught off-guard. George, a stem cell and reproductive biologist, signed up for 23andMe as part of a course he was teaching on the human genome. To make the lesson more interesting, he got his parents to join, too. He did not anticipate what would come next. "I essentially gave my parents the gift of divorce," he said. (George asked that we not use his real name, to protect his family's privacy. All the other names in this section have been changed as well.)

Through the close relative finder program on 23andMe, the family discovered Thomas, a son George's father had conceived and given up for adoption before marrying George's mother. (You can read George's full story here, in this transcript of Vox's conversations with him.)

"I have my PhD in cell and molecular biology," George said. "When I saw that I share about 25 percent of my genome with a person, that there's someone out there that shares 25 percent of me, I thought, ‘That's huge.'"

He immediately called his father and asked him to log into his 23andMe account. His father saw that he was 50 percent related to Thomas and that Thomas was his predicted son. Still, because Thomas was also listed as George's predicted grandfather, George's dad was confused and thought this was just 23andMe's mistake, that there was no real relationship.

George knew better. "I freaked out. I said, ‘Can I call you back later?' I hung up the phone. I pulled out my genetics textbooks, called my contact at 23andMe, and asked if it was wrong. I called my sister, and for three days, we agonized about what to do. We got into a fight. Do we say something? Do we not say something?"

When George figured out his dad had conceived this child before getting married — that the child was not the result of adultery — he was excited. "I thought it was the coolest genetics story, my own personal genetics story. I wasn't particularly upset about it initially, until the rest of the family found out, and their reaction was different."

His mother and sister could not handle the information, and his father went against their wishes, dedicating himself to reconnecting with his estranged son. "Years of repressed memories and emotions uncorked and resulted in tumultuous times that have torn my nuclear family apart. We're not anywhere close to being healed yet, and I don't know how long it will take to put the pieces back together."

After this discovery was made, George went back to 23andMe and talked to them. "I said, ‘I'm not sure all your customers realize that when they participate in your family finder program, what they're participating in what are essentially really advanced paternity tests.'" The person he spoke to "didn't really have a response" for him, he said.

Like Jolie Pearl, George thinks that people should be heavily warned before using 23andMe. "When you check that [close relatives] box it should have a bunch of stars and bells and whistles around it. Because there are plenty of people who click boxes. Nobody reads their iTunes agreement. That's how I feel about the family finder thing — you just check all the boxes, just keep doing it, and never put a whole lot of thought into the possibilities."

He certainly didn't: he just couldn't have imagined this outcome, even with his advanced knowledge of genetics. "One of my favorite phrases is sunlight is the best disinfectant. I still think that's true. But this has challenged that worldview. This is an example where having more information has had a negative emotional and psychological impact."

George's story is echoed in Neil Schwartzman's. The joy of finding Pearl soured about a year after they first met. They have barely talked since. There was no big fight or particular reason, he said. "I think it was part of the embarrassment. It ripped a scab off, the fact that I existed and was given up for adoption in secret."

His presence underscored longstanding tensions within the family. When Pearl tried to figure out who Schwartzman's father was, she discovered that it was the same man who fathered her. Pearl's mother was not happy that they made this connection. "(My mom) began to get very agitated and angry, I think out of embarrassment," Schwartzman said. Maybe it was the uncomfortable fact that she gave up one child and kept the other. "It's very common in adoption reunions that things don't work out, and that's what happened here," he said. Pearl would not comment on their falling out.

Looking back, Schwartzman said the experience was a negative one overall. "But I am glad at the same time that I undertook this journey because it's something very common amongst adoptees," he said. "There is an unrelenting curiosity as to who your parents are when you don't know." It didn't take long for him to have that realization that many adopted kids experience: that his real family isn't his biological one.

With services like 23andMe, whether people realize it or not, keeping family secrets may no longer be an option

"The truth sometimes doesn't need to be known," he said. "The fact that you live your life thinking that somebody is your parent and they turn out not to be and they were cuckolded or they knew and didn't tell you. ... There is a case to be made for the fact that sometimes that stuff is just best to be left alone."

With services like 23andMe, whether people realize it or not, keeping such family secrets may soon no longer be an option.

Direct-to-consumer testing is becoming increasingly affordable and pervasive. Though the clinical application of these services is still in its infancy, and there are those regulatory hurdles to overcome, the consumer demand for DNA testing is there. 23andMe's Anne Wojcicki estimates the industry is worth more than $3 trillion.

As the market grows and more and more people log in, services like 23andMe may well become the Google of our personal genetics. Except instead of acting as the gatekeeper for a search query on how to cook a steak, they will be the guardians of our collective DNA. With quiet changes to their privacy settings, the company is already determining whether and how we have family secrets revealed and how we learn about our histories. It's already controlling the narrative of our genes.

This worries critics like Jasanoff. "It may be statistically true that there are more ‘happy' events than ‘sad' events as a result of such information being made available. But do we really want a private company to decide that it wants us all to have a certain kind of experience with our DNA because the sad events are in a minority?"

Correction: A quotation in this article originally said that the family of Henrietta Lacks must be consulted when scientists use HeLa cells. This is incorrect; the issue of consulting Lacks' family about using or growing HeLa cells has not been resolved. Instead, scientists now have to apply for access to do research on the HeLa genome, which was sequenced last year. The text has been corrected.