Home DNA testing kits are going on sale in Boots stores across the UK later.
Until now, the paternity packs have only been available online and in a few independent pharmacies.
The chemist says it is the first High Street shop to sell the kits, which let people settle disputes over whether someone is father to a baby without outside help.
The kit costs £29.99, with an extra £129 to get the results back from the laboratory.
The couple and the child each rub a cotton swab inside their mouth, put each one in a specially coloured envelope and send them off to be tested.
Results are returned within five days.
DNA kits have been available online for years and in a few smaller chemists since 2009, but Boots says it's now introducing them into 375 of its stores.
Doctor Mandy Hartley from Assure DNA, the company behind the kits, says the results are "99% accurate" but warns that people should think about how they'd feel if the results don't go their way.
"We really do need people to think about the impact of the test," she admits.
"We encourage people to telephone us, or we telephone them and we can also put them in touch with counselling services."
People thinking about a test should also know that taking someone's DNA without permission is illegal in the UK and the results aren't accepted by a court.
Child benefits campaigner, Darren Jamieson from CSAhell.com, also told Newsbeat that making the tests easily available could lead to more couples splitting up and in the long run put more pressure on the Child Support Agency.
The Child Support Agency say they will only accept the results of a DNA test which has come from an approved testing provider and an approved doctor.
They send all DNA testing to one chosen specialist company and they say '' if a father wishes to arrange their own test there are special rules that apply.''
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