Peters' birth certificate records his birth in Whangarei and his registration as Wynston Raymond Peters. His father is of Māori descent and his mother has Scottish ancestry. His iwi affiliation is Ngāti Wai and his clan is MacInnes. Two of his brothers, Ian and Jim, have also served as MPs, and another brother, Ron, has also stood as a New Zealand First candidate. According to the journalist Ian Wishart, Peters had little exposure to the Māori language and culture during his childhood years due to vigorous assimilation policies that encouraged integration into Pākehā (New Zealand European) society.