THE NEW YORK TIMES: For two sisters, a ‘biological age test’ became a ledger of their past

The notification lit up Michelle’s phone at 5.25am on the West Coast: a text from her older sister, Deb, who had an idea.

Deb had heard on a longevity podcast about a new technology that claimed to measure how quickly a person was aging. For $399, each sister could submit a blood sample and learn how her habits and experiences had affected the ways her genes behaved.

The test, called TruAge, could supposedly tell them the functional ages of their brains, hearts, lungs and bodies overall.

“I think it would be super interesting to look at test results between siblings,” Deb, 56, had written. “You interested?”

“Yes, I would love to,” Michelle, 54, replied. “I fear the results, though.”

When it came to their genetics, the sisters seemed remarkably alike. (They asked to be identified using only their first names to discuss sensitive medical information.)

They had the same deep-set, ice-blue eyes; the same prominent cheekbones; the same blond hair that swirled from a cowlick on the back-right corner of their heads.

They both had astigmatism and night blindness; neither could roll her tongue or sing on pitch. And they had the same unusual variant of a gene called ABCC11, which meant their armpit sweat never had any odour.

Deb and Michelle, raised together in Detroit, knew they shared roughly half their DNA, but sometimes they had a hard time believing it.

Deb, who now lived in Virginia, had always been hyperdisciplined, pragmatic and outgoing. A former Air Force nurse, she had traveled the world, raised three children and seemed to exercise nonstop.

Michelle was sensitive and bookish — so introverted that she didn’t even own a calendar. She had settled into the central valley of California after high school and never married. She lived a quiet, contented life with one companion: her Herder-Pit mix, Merlin.

There was another key difference: Deb had always been healthy, aside from mild joint pain and high cholesterol that medication kept under control. But Michelle had been obese in her teens and 20s and later struggled with autoimmune issues that no doctor had been able to fully explain. Every day was some constellation of extreme fatigue, nerve pain and tachycardia from low blood pressure. When Deb’s text arrived, Michelle was dealing with swollen lymph nodes, bumps all over her hands and a rash that stretched into her ear canals and nostrils.

Deb told her sister that maybe the test could help her better understand the causes and effects of her ailments. After years of feeling dismissed by doctors, maybe Michelle would feel validated if her biological age reflected her suffering.

Deep down, Michelle had a feeling that Debbie — she would always be Debbie to Michelle — just wanted to outperform Michelle.

Still, Michelle wasn’t going to miss the first opportunity in years to do something with her sister. As adults, the two had grown distant, and then, after a bitter fight, stopped talking at all for almost two decades.

They had reconnected only a few years ago, and even now, only through texts.

“Do you have a website so I can look at it?” Michelle asked.

The test’s marketing materials promise “the most complete picture of how your body is aging.”

It analyses almost one million chemical tags on DNA that make up a person’s epigenetics, the layer of biological instructions that controls how someone’s genes are expressed.

By comparing a person’s unique pattern against large databases of other people’s results and health outcomes, its models try to assign an “age” that reflects the person’s predicted level of health.

Both sisters packaged their blood samples and dropped them at their post offices, the envelopes addressed to the same lab in Kentucky.

Deb’s biohacks

Years ago, to stay healthy, Deb had started walking 15,000 steps per day, strength-training at the gym and keeping a sugar-free diet.

But as Deb became more interested in longevity, she added more habits, until she was using red light therapy daily, taking pills to increase antioxidant production and mitochondrial function, and experimenting with acupuncture and herbal patches.

She didn’t have a primary care doctor, and she didn’t think she needed one. All of her biohacks were already based on personalised insights.

She had done a test to check for calcium buildup in her heart’s arteries, multiple scans to measure the strength of her bones, and a mail-order analysis called the 3X4 Blueprint that supposedly revealed which genes made her more susceptible to dementia, chronic inflammation and connective tissue decay.

Deb fed all her health information into ChatGPT, which then guided her to the best vagus nerve stimulators, chemical peels and fibre gummies — and more assessments.

It was ChatGPT that had convinced Deb to order the TruAge test in the first place.

“You’ve spent the past year optimising almost every major longevity lever,” the chatbot told her after she asked it about the test’s value. TruAge, it said, “can help answer whether the protocol you’ve assembled is changing your biological trajectory.”

Childhood turmoil

Deb, a master compartmentaliser, preferred not to think about her mother’s erratic outbursts; their parents’ volatile fights; the constant extramarital affairs, which the girls often knew about.

Sometimes the adults would disappear for long stretches of time, leaving the sisters to forge notes to their teachers and fend for themselves.

Increasingly, their paths had differed: Deb grew long and thin and gregarious, while Michelle withdrew behind more and more weight. Deb became a cheerleader, earned straight A’s and spent more time with her boyfriend’s family than her own.

Deb couldn’t remember the details of their estrangement, but Michelle had long been a painful reminder that Deb, as the elder sister, needed to be the adult in the house, even when she was still a child.

She was pretty sure the breaking point had taken place in their 30s, when Michelle got wrapped up in a horrible relationship with a guy Deb couldn’t stand. Deb had always been able to cut anyone out of her life without a second thought, so she did.

Then, after almost 20 years, Michelle reached out in a text message, apologising for her role in the conflict.

They began messaging again, but when Michelle called, Deb sent it to voicemail and texted her instead. Something about the thought of actually speaking to Michelle set off panic in Deb’s chest, even now.

Deb had always expected that her biological age would be younger than Michelle’s. But in the silence of her empty house, she began to consider other possibilities.

What if Deb’s heavy partying in her 20s had super-aged her liver? What if her natural cholesterol levels, which were beyond her control, were causing vascular damage? What if her younger sister “had been able to trick her body in some way,” Deb wondered, and prove that all of Deb’s protocols were for nothing?

Two centuries of clinical experience

Michelle had not dwelled much on the test since she’d taken it. A part of her thought the whole thing might be pseudoscience.

Michelle had at least seven specialists in a regular rotation, including an allergist, a neurologist, a podiatrist and a dermatologist — almost two centuries’ worth of collective clinical experience that still left her “playing connect-the-dots,” she said.

She was dubious that a few drops of blood were going to finally reveal the full picture.

But Michelle had a mental health counseling degree and read more than 200 books a year, many of them about psychology.

She had been thinking lately about the ways toxic stress might leave lasting scars on human DNA. Now she couldn’t help but wonder if the kit’s algorithms might be programmed to measure something deeper.

As a child, Michelle had internalised the turmoil in their home — a factor she believed contributed to her rashes and sinus infections and overeating.

She remembered the way their mother would throw items like screwdrivers and books at them, the maggots in the food when she and Deb were routinely left alone for weeks.

The trauma of their childhood had coloured the first half of Michelle’s life. She ate addictively until she was 342 pounds and needed weight-loss surgery.

She gravitated toward abusive relationships, staying in one for 14 years. And then, one night in 2007, Michelle was attacked by three men in a Walmart parking lot and sustained a traumatic brain injury, broken facial bones and a blown-out eardrum that left her partly deaf.

That was when Michelle decided to invest in “holistic healing,” she said.

She earned her counseling degree, took a job with a disability advocacy group and started volunteering at a homeless shelter. She also eventually reached out to Debbie.

Michelle finally found her stability — not in her physical being, but her emotional one.

Sometimes she suggested that Debbie consider therapy. But Debbie had no interest. Now Michelle wondered: Could all that compartmentalization have done something to Debbie’s cells?

The results

Deb had been refreshing her TruAge online portal every couple of days, but Michelle’s results landed first. They ran to 73 pages of data, including stress markers, nutrient levels and toxin exposures.

Plastered across the top were three key metrics: an overall score that encompassed a lifetime of chemical tags; another that measured the “pace” at which the body was supposedly aging; and, finally, a score that focused on the body’s organs, looking at markers associated with 11 different systems.

Michelle leaned back in her recliner and began to scroll.

There was no sugarcoating the first score: Although Michelle was just 54, the test declared her overall “biological age” to be 62.

But the other two delivered what seemed like good news. Her aging “pace” score said that for every year that passed, she would age only 0.98 years — an indicator of a healthy lifestyle in recent months.

And her organ ages surprised her even more: All 11 organ systems together averaged to a relatively youthful 53.4. Her lungs were 53.6; her brain was 53.8, despite her traumatic brain injury. And even with all of Michelle’s autoimmune issues, her inflammation system was, inexplicably, 52.4.

Weeks later, Deb received her results. She clicked into the portal, leaned closer to the screen and swallowed. The 56-year-old’s overall score was 58.3 — higher than she would like, but still younger than her sister’s. And she was aging at a pace of 0.90 each year — good news.

But then she scrolled down to the organ results.

Every result seemed astronomical. They averaged out to 63.5, more than a decade older than Michelle’s. Many were even scarier: Her lungs were 64.7. Her heart was 64.3. Her liver was 63.9. Her immune system was 66.7, compared with her immune-deficient sister’s 57.8.

Deb closed her laptop and got ready for work, but she spent the day in a private vortex of grief.

Had she exercised too hard the day before she took the test, or not slept enough? Or maybe the results were accurate, and no amount of effort could override her unlucky DNA. Either way, she didn’t know what to do next.

That was the problem many health experts had with biological age test results: There was no consensus on how to act on them.

A doctor would have told Deb not to worry much about her scores, to focus instead on age-old advice: Stay active, eat healthfully and enjoy her years. But the emotional undertow of the wellness era seemed to suggest that was no longer enough.