Gwen John was born in Haverfordwest, Wales, the second of four children of Edwin William John and his wife Augusta (nee Smith). Edwin John was a solicitor whose dour temperament cast a chill over his family, and Augusta was often absent from the children due to ill health, leaving her two sisters??stern Salvationists??to take her place in the household. Despite the considerable tension in the family (who became known as "those turbulent Johns") the children's interest in literature and art was encouraged. Following the mother??s premature death in 1884, the family moved to Tenby in Pembrokeshire, Wales.
Although she painted and drew from an early age, her earliest surviving work dates from her nineteenth year. From 1895?C98, she studied at the Slade School of Art, where her younger brother, Augustus John, had begun his studies in 1894. During this period they shared living quarters, and further reduced their expenses by subsisting on a diet of nuts and fruit. Even as a student, Augustus' brilliant draughtsmanship and personal glamour made him a celebrity, and stood in contrast to Gwen's quieter gifts and reticent demeanour. While he greatly admired her art, Augustus offered her advice which she ignored; he urged her to take a "more athletic attitude to life", and cautioned her against what he saw as the "unbecoming and unhygienic negligence" of her mode of living, but her entire life was marked by a disregard for her physical well-being. In 1898 she made her first visit to Paris with two friends from the Slade, and while there she studied under James McNeill Whistler at the Academie Carmen. She returned to London in 1899, and spent the next four years in austere circumstances. When she exhibited her work for the first time in 1900, at the New English Art Club (NEAC), her address was a derelict building where she was living illegally.