Ann Matthews, Iolo's mother, was raised at Boverton, near Llantwit Major. She married Iolo's father, Edward Williams, senior, in St Athan's church on 8 November 1744. She was the daughter of Edward Matthews of Ty'ncaeau in the parish of Coychurch. When she was nine, her mother died and her father sold his inheritance. As a result, Ann was raised by her mother's sister, who had married into the Seys family of Boverton.
His mother's privileged upbringing influenced the self-image which Iolo projected to the English literary world. Her firstborn child had died, and when Iolo was born Ann cossetted him. In the preface to Poems, Lyric and Pastoral (1794) Iolo claimed that he was his mother's favourite child. Indeed, some critics argue that Iolo's close relationship with his mother explains his complex psychological make-up: his egotism, inferiority complex and tendency to romanticize the past.