If you've ever been curious about your cultural heritage or family tree, you might have considered taking an online ancestry DNA test.
The affordable pricing and simple process of direct-to-consumer DNA kits means the tests also make popular gift ideas.
It's estimated more than 26 million people globally have undertaken ancestry DNA testing through direct-to-consumer companies.
While some see it as "a bit of fun", and may experience positive outcomes like connecting with family, others get more than they bargained for, explains Jane Tiller.
She's an ethical, legal and social adviser in public health genomics at Monash University.
"People don't always expect [their results] can have a dark side — the family tree might not be what they expect," Dr Tiller says.
Where your sample is stored, and how your data is used, is also worth consideration.
In 2023, hackers stole the profile and ethnicity information of millions of people from one such company — 23andMe.
That same company is now on the verge of bankruptcy, with its CEO considering selling the company, which means the DNA of its 15 million customers would also be up for sale.
Andelka Phillips is an academic affiliate at the University of Oxford and author of Buying Your Self on the Internet: Wrap Contracts and Personal Genomics.
She says most people don't take the time to read the lengthy online contracts and privacy statements for 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."
What DNA testing is available and how accurate is it
Whether you want to learn about family, your health, or what sport you should play, there is a spectrum of direct-to-consumer DNA testing available.
Dr Tiller categorises ancestry testing as "recreational genetics".
"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 company to company.
Genetic testing for medical information is evidence based, although Dr Tiller says what you can access online will vary depending on where you are located.
For example, in Australia, it is not legal to offer a test regarding the BRCA gene (which can be associated with a range of cancers including breast cancer) direct to consumer.
Dr Tiller says "low on evidence" tests include those that claim to tell you what exercise regimen would suit you best, or what wine you might like to drink.
Dr Phillips says products that concern her most are those that encourage you to send in a child's DNA to "test their talents" or IQ, for example.
Not only because they lack evidence, but there isn't informed consent.
"If you think about sending a child's sample off, we don't know how long it will be stored, what it might be used for, how it might be used against their interests in the long term," Dr Phillips says.
Other problematic products include "infidelity" testing, which she says is not evidence-based or ethical.
"[These companies that claim to test] infidelity are really preying on people and encouraging people to send in samples if they are concerned their spouse or partner might be cheating — without their consent.
"Really dodgy."
'Be prepared' for ancestry test results
For people who are aware they are adopted or donor conceived, genealogical DNA testing may be less about recreation, and instead necessary to connect with biological family where records are otherwise inaccessible.
For others who may uncover unexpected family connections, there can be feelings of betrayal and identity confusion, explains Jo-Ann Sparrow.
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.
"Many people describe the experience as life-altering, leading them to question their identity, family history, and relationships."
Dr Sparrow says it's important to prepare for the possibility of uncovering unexpected family secrets.
"If you discover unexpected connections — such as an unknown biological parent or sibling — you may want to reach out to a post-adoption or donor-conceived support service in your state or territory for guidance."
In more extreme cases, Dr Phillips says people may discover they are linked to something criminal or distressing.
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.
"It also may not be accurate."
Dr Phillips says if appropriate, you can let family know you are thinking about taking the test, given you share DNA with biological relatives.
"Where people don't know they are donor-conceived or adopted … if you are on good terms with your family, it's probably good to just have a chat about the fact you are doing the test.
"Once one person's DNA is in the system, that does create some privacy implications for other family members … your parents, siblings, children, even your grandchildren."
Where does your data go and what can it be used for?
People may not be aware DNA testing companies may have partnerships that allow their data to be used in other ways.
"23andme [for example] did have partnerships with pharmaceutical companies, there's always been this tendency to reuse the data for research," Dr Phillips says.
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 you often are with these tests, "you have to know your country's laws cease to have any impact," says Dr Tiller.
Dr Phillips say data leaks and privacy issues also need to be considered.
"Generally, once someone has a DNA test, their DNA is sequenced, and that will generate their digital code.
"That information is a unique identifier for the individual that isn't going to change over time."
She says the risk of a data breach doesn't necessarily decrease over time either, because it could impact children, grandchildren and so forth.
"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?"
While ancestry is the type of direct-to-consumer DNA testing Dr Phillips is most "cautiously positive about", she doesn't think it is "safe for everyone"
"I'm not anti-industry, but this is an industry that really needs better oversight and standards."
