Mullin was born in South Africa, and first discovered volleyball while living in Malaysia.

[1] Her father was a hotel manager, so Mullin's family moved around a lot while she was a child and she spent time in boarding schools.

[citation needed] In 1999, her family moved to Edinburgh, Scotland, she took a master's degree in Management with Business Law at Heriot Watt University.

[3] Whilst on the tour, along with her partner Zara Dampney, she sold advertising space on the back of her bikini bottoms, hosting a QR code for bookmaker Betfair.

[4] They competed at the Olympic test event in London, and won all of their group games, but were defeated in the second knockout round by the Brazilian team who went on to win the tournament.