John Cleland was the eldest son of the Scot
William Cleland (1673/4 – 1741) and Lucy Cleland (née DuPass). He was born in Kingston upon Thames in Surrey but grew up in London, where his father was first an officer in the British Army and then a civil servant. William Cleland was a friend to Alexander Pope, and Lucy Cleland was a friend or acquaintance of Pope, Viscount Bolingbroke, Chesterfield, and Horace Walpole. The family possessed wealth and moved among the finest literary and artistic circles of London.
John Cleland entered Westminster School in 1721, but he left or was expelled in 1723. His departure was not for financial reasons, but whatever misbehaviour or allegation had led to his departure is unknown. Historian J. H. Plumb speculates that Cleland's puckish and quarrelsome nature was to blame, but whatever caused Cleland to leave, he entered the British East India Company after leaving school. He began as a soldier and worked his way up into the civil service of the company and lived in Bombay from 1728 to 1740. He returned to London when recalled by his father, who was dying. Upon William's death, the estate went to Lucy for administration. She, in turn, did not choose to support John. Meanwhile, Cleland's two brothers had finished their education at Westminster and gone on to support themselves.