If you unwrapped an online ancestry DNA test for Christmas, you might be feeling curious — even excited — about discovering your cultural heritage and family tree.
But did the accompanying card warn it could also blow up your life?
Before you spit in the tube and join the more than 26 million people globally who have undertaken ancestry DNA testing through direct-to-consumer companies, there are some important things to consider.
Getting more than you bargained for
For people who know they are adopted or donor conceived, genealogical DNA testing may be useful and necessary to connect with biological family when records are otherwise inaccessible.
But if you're taking these tests as just "a bit of fun", know there is the risk of uncovering more than you are prepared for, explains Jane Tiller.
"People don't always expect [their results] can have a dark side — the family tree might not be what they expect," says Dr Tiller, an ethical, legal and social adviser in public health genomics at Monash University.
Uncovering unexpected family connections can be "life-altering", says Jo-Anna Sparrow, leading to feelings of betrayal and identity confusion.
She is the president at Jigsaw Queensland, an organisation that provides information, support and referrals for people impacted by past adoption practices, including those who discover they are adopted later in life.
"Some learn they were adopted, or donor conceived [through DNA testing]," explains Dr Sparrow.
"Common reactions include shock, disbelief, anger, confusion, and a sense of betrayal — especially if the truth was hidden by loved ones."
While sometimes surprising results can lead to positive outcomes, experts warn it's important to be prepared for the potential impact of uncovering a "family secret".
In more extreme cases, people may discover they are linked to something criminal or distressing, explains Andelka Phillips.
She is an associate professor in the law school at the University of Leicester and academic affiliate with the HeLEX Centre, University of Oxford.
For example, a fertility doctor using their own sperm to inseminate patients, or IVF companies using the "wrong sperm" to conceive children.
There can also be cultural implications, Dr Phillips explains.
"Ethnicity [testing] is not standardised, and it might impact your view of your cultural or ethnic identity."
What will happen to your data?
Where your DNA sample is stored and how your data is used are other considerations.
In 2023, hackers stole the profile and ethnicity information of millions of people from one such company — 23andMe.
Dr Philips says most people don't read the fine print of genealogical DNA testing.
"The price of these kits has dropped a lot … the profit [these companies] make is from the data and partnerships that emerge from having a large data base.
"23andme did have partnerships with pharmaceutical companies, there's always been this tendency to reuse the data for research."
In Australia, genetic data is protected as "sensitive information" under the Privacy Act, but that doesn't mean it's untouchable.
And if you are sending your DNA to another country, as often is the case with these tests, "you have to know your country's laws cease to have any impact," says Dr Tiller.
Dr Phillips says people should think about privacy issues and be aware data leaks are possible.
Data breaches can also impact children, grandchildren and so on, she says.
"Taking any of these tests, you need to think about how comfortable you are with the privacy of your data.
"Would it matter to you if your data was leaked in a breach? Would it be a problem for you if you couldn't get insurance coverage because of having a test?"
Is ancestry testing accurate?
There is a spectrum of direct-to-consumer DNA testing available, including genetic testing for medical information.
Dr Tiller categorises ancestry testing as "recreational genetics", and says accuracy is not guaranteed.
"There is a reasonable degree of evidence behind what you get back — but over time that might shift, as that evidence base is still developing."
She says ancestry testing is not standardised, so results may vary from company to company.
Dr Phillips says being informed is vital before taking this type of test.
"I'm not anti-industry, but this is an industry that really needs better oversight and standards."
A version of this story was originally published in March 2025, and has been updated.
