1840 census of Adams Co., Ohio, Tiffin township, lists on p. 4A, line 8:
Isaac Petit, 1 male 30-39, 1 female 30-39; 1 m < 5, 1 m 5-9, 1 m 10-14; 2 f < 5, 1 f 5-9.

1850 census of Adams Co., Ohio, Tiffin township, enumerated 31 Aug, lists on p. 42 as family #1552:
Isac Pettit, 41, blacksmith, b. Ohio; Sarah, 43, b. Pa; Mary A., 17; Isac J., 16; John M., 14; Sarah, 12; Margaret A., 10; Wm H., 8; Chambers, 7; Washington, 5. All children born in Ohio.

1860 census of Adams Co., Ohio, Oliver township, Dunkinsville P.O., enumerated 26 July, lists on p. 147 as family #1065/1071:
Isaac Pettit, 49, blacksmith, b. Ohio; Sarah, 53, b. Penn.; John M., 23; Margaret A., 20; Joseph C., 17; George W., 15; Sarah M., 7; Mary A., 2. All children born in Ohio.

The children Sarah and Mary are probably granddaughters; Isaac and Sarah had a daughter named Mary born about 1832 and a daughter Sarah born in 1838 who was still living. Their surname may not even be Pettit; see the 1870 census.

1870 census of Adams Co., Ohio, Oliver township, Wheat Ridge P.O., enumerated 4 June, lists on p. 15 as family #115:
Pettit, Sarah, 66, b. Penn; George W., 23, school teacher, b. Ohio. Waldron, Sarah N., 17, b. Ohio. McGowan, Mary A., 11, living in family, b. Ohio.

It is likely that Sarah Waldron and Mary McGowan are the Sarah age 7 and Mary age 2 who were living with the family in 1860, with their surnames entered incorrectly then. (Sarah is old enough to have been a Pettit who was recently married and then widowed young, but if the correct surname was left off for one of the foster children in 1860, it is likely to have been so for both.)