 Duffy was born on 23 June 1984 in Bangor, Gwynedd, and was brought up by her parents; John Duffy and Joyce Smith (née Williams) in Nefyn, near Pwllheli.She has a twin sister, Kate, and an older sister, Kelly Ann, who was born in 1980.Duffy's parents divorced when she was 10 and she moved to Letterston, near the Pembrokeshire town of Fishguard, with her mother and sisters.