Relativity was a Scots-Irish quartet formed in 1985 consisting of two Scottish brothers and an Irish brother and sister. The four members of the band were brothers Johnny Cunningham (fiddle) and Phil Cunningham (accordion, keyboard, whistle, bodhran), from the influential Scottish band Silly Wizard, and Irish sister and brother Tríona Ní Dhomhnaill (vocals, clavinet) and Mícheál Ó Domhnaill (vocals, guitar, keyboard) from the influential group The Bothy Band.