The John Adair of York Co in the SC 1790 census appeared to be a single man.
Not sure if John Adair, Gov. of Kentucky, had moved from SC by then.Here is one version of a possible connection, but this is subject to verification.Perhaps there may be information in the "J.B. Adair book" onBurrel / Burrell Stevens / Stephens ?
"Notes from Dawn Brown crickethunter at juno.com Nancy Adair was a near relative of General John Adair, Governor of Kentucky. General John Adair was born in Chester Co., S. C. in 1759. He fought in the Battle of New Orleans, Jan 8, 1815; commanded Kentucky Militia, was a member of Congress from Kentucky and died in 1840.
Sometime after the death of Harris Tyner, Nancy Adair Tyner married Burrel Stevens and her children by him were: Shadrick, Susan, Elial, Ezekiel, and Betsa. Elial and Ezekiel moved to Indiana, but the others stayed in Carolina and Georgia. Elial died in Wabash County, Indiana."