Thomas Turpin was Thomas Jefferson's uncle by marriage. He was married to Mary Jefferson, Peter Jefferson's younger sister. Turpin was one of the five executors of Peter Jefferson's estate,and thus bore some degree of fiscal and material responsibility for Thomas Jefferson and his mother and siblings after Peter Jefferson died in 1757.1
In 1769, Turpin apparently approached Jefferson about superintending the studies of Turpin's son Philip. Jefferson offered his uncle a "plan of study" for his young cousin, but regretted that he would not be able to offer further assistance. Jefferson explained that he was busily in the process of relocating from Shadwell to "another habitation which I am about to erect," the earliest surviving reference to Jefferson's building plans for Monticello.2
While Governor of Virginia, Jefferson rented and resided in a house in Richmond that was owned by Thomas Turpin. The house was located on Shockoe Hill, probably just a little south of where the governor's mansion stands today, near the intersection of 12th and Franklin Streets.3
Over the years, Jefferson also remained in touch with Thomas Turpin's sons, his cousins Horatio and Philip Turpin.4
2. Jefferson to Turpin, February 5, 1769, in PTJ, 1:23-25. Transcription available at Founders Online.
3.MB, I:495, 495n72. See also Turpin to Jefferson with Reply, December 22-23, 1780, in PTJ, 4:224-25. Transcription available at Founders Online.
4. See, e.g., Jefferson to Philip Turpin, July 29, 1783, in PTJ, 6:324-30 (transcription available at Founders Online), and Jefferson to Horatio Turpin, June 10, 1807, Gilder-Lehrman Collection, New-York Historical Society (transcription available at Founders Online).