Edward Venn (1717—1780) was a doctor in Ipswich. His father, Richard Venn (1691—1739) was a vicar, as was his father before him and so on in “an unbroken succession of clergymen from the time of the Reformation”, as the DNB puts it. The Venn family “for generations produced parsons for the Anglican church one after the other like eggs from a hen” in James Hamilton’s delightful phrasing .
But not Edward, although as the eldest son he might have been expected to, and his brother Henry (1725—1797) carried on the family tradition and was a prominent Victorian theologian. Henry was also the great-grandfather of the Rev. John Venn (1834—1923) of Venn diagram fame.
What of Edward? He began by following the usual course, going up to Cambridge in 1737 and taking BA in 1740 and MA in 1744 as a first step towards a clerical career, but at some point he veered off course. Perhaps he had a little more leeway as his father had died (of smallpox) in 1739. Instead of the church he went to Leiden to study medicine and then moved to Ipswich to practice as a physician.
The only discussion I have found of Edward’s change of heart is in the Venn family history, Annals of a Clerical Family, which records:
He studied at Cambridge with great diligence, intending to have taken orders. But, having passed his degrees, some obstacles presented themselves to his mind with regards to subscribing to the Articles of the Church of England. By this I do not mean that he actually left her Communion and attached himself to any other sect, but only insomuch as related to his becoming a minister. He therefore devoted himself to the study of medicine, and became a pupil of the famous Dr. Heberden.
No further particulars are given of his religious scruples.
At Ipswich Edward Venn led the quiet life of a provincial doctor and is largely absent from the record until his brief obituary in the local paper, the Ipswich Journal, “On Sunday last died Dr. Edward Venn, an eminent physician in this town, universally regarded(?) for his amiable character in private life, as well as for his abilities in his profession”. Apart from that, he at one point owned a dog called Sappho, and he subscribed to the first edition of Joshua Kirby’s Method of Perspective.
Edward Venn married Mary Beaumont (1716—1796) of Witnesham and they had two children, a daughter Mary (1750—1811) and a son Edward (1752—1830).
 Hamilton, J. A Strange Business, p. 25.