Andrea was born to Gerry Corr, a manager of the payroll department of the Irish Electricity Board, and his wife, Jean, a homemaker. They raised their family in Dundalk, Ireland. Gerry and Jean had their own band, Sound Affair, which played songs by ABBA and The Eagles in local pubs where they would often bring along their children.

With the encouragement of her parents, Andrea took up the tin whistle and was taught the piano by their father. Throughout their teenage years, she and her siblings would often practice in Jim's bedroom at a house he had rented. Andrea sang lead vocals, Sharon played the violin and both Caroline and Jim played keyboards. Moreover, Andrea took part in school plays at her school, Dundalk's Dun Lughaidh convent.