Both Kit's mother (Margaret) and Kit's Aunt Rachel (the sister of Margaret) were born in England. However, these sisters took very different paths in life: Margaret moved to Barbados, giving birth to Kit there, while Rachel married Matthew and went to live in a Puritan colony in Wethersfield, Connecticut.
Margaret died in Barbados, leaving Kit to be raised by her wealthy grandfather, Sir Francis Tyler, who--unlike the Puritans--was loyal to King Charles I and to the Church of England. After Sir Francis died, Kit made the difficult decision to leave behind her life of luxury and to join her Aunt and Uncle in Wethersfield. Although this resulted in her facing many difficult circumstances--including accusations of being a witch--Kit managed to overcome them.
As a final note: at the end of the novel, Aunt Rachel is still alive, but it is safe to assume that when she does die, it will be in her community in Connecticut.