In January 2012, Little Mix begun recording songs for their debut album. The group worked with production team TMS, and Iain James on a number of songs at The Music Shed in London, England, four of which were chosen for the album. One of these four songs was "DNA," which subsequently became the title of the album. The song originated from the group's personal experiences in romantic situations. The group wanted to create a song about their own experiences so that they could improve the quality of their live performances. Edwards said: "We perform better when the lyrics mean something to us when we sing them." "DNA" was developed to manifest a completely different side to Little Mix. When creating the song, Little Mix took into consideration which of their performances during their time on The X Factor was the most popular. Their performance of Katy Perry's "E.T." was the week during The X Factor where the group received the most votes. The group's version of "E.T." was perceived as "quite dark" by Jade Thirlwall, in turn, Thirlwall said that the group wanted "DNA" to showcase a darker side of the group. Thirlwall told Sarah Dean of The Huffington Post that the song was also inspired to show how the group has grown in maturity.
Jon Hornbuckle of So So Gay described "DNA" as "an addictive slice of dark pop, with the chorus breakdown remaining not only a highlight on this track, but of the entire album." The song was well-received by Vicky Newman from Shields Gazette, who felt that it demonstrates the group's "stunning" harmonies and allows their voices to "shine". Newman also wrote that the song's urban edge manifests Little Mix's growth and development. Gigwise's Andrew Trendell praised the track's production, writing, "The skittering beats and little quirks of 'DNA' make it instantly memorable." Adrian Thrills of the Daily Mail complimented the song's choral middle-eight, deeming it "an inventive sonic flourish". "DNA" was described as "pop perfection" by Lewis Corner of Digital Spy, who highlighted the song's "spooky synths, pumping heartbeats and gothic choir finale". John Earls from British newspaper, Daily Star, positively reviewed the single, calling it "a winning formula," in addition to awarding it a nine out of ten rating. Earls went on to mention that the song is "A regal anthem that will have all of Girls Aloud wondering how they didn't release it first, the Little Mixers are sounding huge at last.". "DNA" was deemed "amazing" by Clemmie Moodie of the Daily Mirror. Eve Barlow for NME likened the song to Katy Perry's "E.T." and described it as "a banger"
"DNA" debuted and peaked at number eight on the Irish Singles Chart for the week ending 15 November 2012, becoming Little Mix's third consecutive top ten hit in Ireland. After descending the chart for 12 weeks, the song dropped off on 14 March 2013. It then re-entered the chart at number 93 on 28 March 2013, before dropping off two weeks later. It spent a total of 14 weeks on the chart. In the United Kingdom, "DNA" was a contender for number one when it was revealed that the single was at number two in the midweek chart, 3,000 copies behind Bruno Mars' "Locked Out of Heaven". By the end of the week "DNA" entered the UK Singles Chart at number three on 24 November 2012 with sales of 72,044 copies, behind "Locked Out of Heaven" at number two (75,880 copies) and One Direction's "Little Things" at number one (85,308 copies). It became Little Mix's third consecutive top three hit in the country and went on to spend a total of nine weeks on the chart, and end the year as the 115th best-selling single in the UK. 
On 12 September 2012, it was revealed that Little Mix were filming the music video for "DNA". A lyric video for "DNA" was posted on Little Mix's Vevo on 1 October 2012. The song's music video was directed by Sarah Chatfield, shot against a green screen for special effects. Prior to the official music video's release, Little Mix begun a countdown to the video's premiere by posting teasers of the video on their Vevo account. In an interview with Linds Foley of Sugar on 8 October 2012, Little Mix promised that the music video for "DNA" will show their fans a completely different side to the group. On 15 October 2012, the group confirmed that the video will premiere online on 19 October. Little Mix told Capital London on 18 October 2012 that they loved getting to play dark characters in the video. Speaking to the radio station, Jesy Nelson mentioned how fun and exciting the filming of the music video was. Nelson pointed out that the reasoning behind their excitement was because of how the video for "DNA" was completely different to the video for their previous single "Wings". During the interview, Leigh-Anne Pinnock explained that each member of the group plays a character in the music video, and admitted she enjoyed getting to act more in the video. Pinnock said, "I loved being able to play ... this obsessed weird person that's just crazy over this guy." When filming the music video, Little Mix made use of the song's themes of love and obsession, depicting it to greater extremes.
The music video sees Little Mix adopting a new heavier look including leather outfits, bullet chains and gothic makeup, and explores themes of jealousy and obsession.It features the group hunting down men who have wronged them.Filmed in comic book movie style, Little Mix play female assassins who stalk and then kidnap men they are obsessed with. In one scene, Perrie Edwards is angrily driving a car while next to a male passenger who is bound and gagged. Edwards sports glossy red lipstick and a biker jacket, keeping her eyes on the road and paying no mind to the camera as wind blows through her hair.
Jade Thirlwall is seen stalking a man outside his bedroom window.Standing outside the window ledge, Thirlwall spies on a man who captured her heart.Thirlwall wears metallic silver and black striped high waisted trousers, with a white shirt, black bow tie and braces and sports purpleish-pinkish hair. Jesy Nelson's scene is similar to that of Edwards. Nelson races to her destination in a vintage convertible with a lace visor covering her eyes as police sirens flash behind her
In another scene, Leigh-Anne Pinnock masterminds the story's plots in a secret room with a wall of evidence the group has compiled, of which includes maps and clippings. Pinnock has her hair slicked back in a long quiffed jet black ponytail, and wears an outfit that resembles that of fictional character Cat woman. The name 'Ryan' is scrabbled across the wall, and Pinnock bangs her fist against the wall. The group come together for a dance routine on a rooftop with a backdrop of dark grey skies and strikes of lightning. All four group members are also seen pacing through a dark city wearing figure hugging outfits.The video draws to a close when the man who the group have built an unhealthy fixation to is seen tied to a chair as the group walks towards him, before the words 'To Be Continued' appear on the screen. In an interview with Owen Myers of Popjustice, Jesy Nelson said the music video will be continued on their 2013 DNA Tour.