His grandfather, also called John Aikin (1713–1780), was a Unitarian scholar and theological tutor, closely associated with Warrington Academy.
[2] He was adopted as a child by his aunt, Anna Laetitia Barbauld, a poet, essayist, literary critic, editor, and children's author.
From an early age he devoted himself to science, and aided his eldest brother Arthur in his first published works and public lectures.
Subsequently he applied himself to medicine, became a member of the Royal College of Surgeons, and was chosen secretary of the Medical and Chirurgical Society of London.
Gilbert Wakefield; one of their children was the writer and memoirist Anna Letitia Le Breton.