Possibilities for his parents include John McClain who married Rebecca Weaver on 6 June 1814, and James McClain who married Minerva Goodhue on 27 May 1824, both marriages in Fleming Co. (The latter marriage would be after John’s birth, but it might be a second marriage.)

1850 census of Fleming Co., Ky, division 2, enumerated 5 Sep, lists on p. 60 as family #419:
Martha Reeves, 65, b. Va; Clarenda, 28; Elizabeth, 25; Sibby Ann, 23; Nancy, 21; Missouri L., 6. All daughters and Missouri born in Kentucky.

Missouri is Sibby Ann’s daughter out-of-wedlock. According to her death certificate, her father was John McClain, whom Sibby later married.

Fleming Co., Ky marriage records list the marriage on 22 Dec 1855 of John McClain, age blank, and Sibby McClain, age 30, first marriage for both, both born in Fleming Co.

1860 census of Fleming Co., Ky, district 2, enumerated 1 Sept, lists on p. 122 as family #872/950:
John S. McLain, 38, laborer; Sibby A., 36; Tennessee, 9; James W., 3; Nancy J., 2; Isaac N., 5/12. All born in Kentucky.

1870 census of Fleming Co., Ky, Hillsboro precinct, enumerated 11 Aug, lists on p. 34 as family #229/226:
McClain, Jno S., 49, farmer; Syda, 45; Jas W., 14; Nancy J., 12; Isaac N., 10; Jno H. M., 7; Henry B. L., 2. All born in Kentucky.

1880 census of Fleming Co., Ky, Hillsboro precinct, enumerated 4 June, lists on p. 7 as family #58/59:
McLane, John S., 58, b. Ky Ky Ky, farmer; Sibeann, 52, wife, b. Ky Ky Va; James W., 23, son; Isaac N., 19, son; John M., 16, son; Henry B., 11, son; Harison L., 7, son. All children born Ky Ky Ky.