His gravestone says that he was born 1830, but it is likely off by at least 10 years. (A birthdate in 1830 would mean that he married at age 13!)

1850 census of Floyd Co., Virginia, western district 15, enumerated 5 Sep, lists on p. 127 as family #907:
Benjamin Dunkin, 33, farmer; Nancy, 23; Julian, 6; Ananias, 5; Minerva, 4; Asa, 2; Eliza, 2/12. All born in Virginia.

The preceding household is headed by John S. Dunkin and wife Rody, both age 64. The next household is headed by Thomas Dunkin age 34 and wife Patsy age 25.

1860 census of Floyd Co., Virginia, Indian Valley P.O., enumerated 30 July, lists on p. 120 as family #937/876:
Benj Duncan, 44, farmer; Nancy, 35; July A., 16; Ennis, 14; Manerva, 13; Asa, 11; Deliliah, 10; Sarah, 8; Francena, 6; Melina, 4; Rebecca, 2; infant (f), 4/12. All born in Virginia.

The daughter listed as Delilah age 10 is presumably the same one who was recorded as Eliza age 2 months in 1850.

1870 census of Floyd Co., Virginia, Indian Valley township, enumerated 19 Aug, lists on pp. 14-15 as family #92/86:
Duncan, Benjamin, 52, farmer; Nancy, 45; Julia Ann, 26; Minerva, 23; Asa, 21; Deliliah, 20; Sarah, 18; Fransina, 16; Melina, 14; Rebecca, 12; Nanzilla, 9; Emmazetta, 7; Noah J., 4; John B., 1; John S., 82, invalid; Rhoda, 82; Crockett, 16. All born in Virginia.

The daughter Nanzilla may be the same as the unnamed infant age 4 months in 1860, although if so, she should be 10. On the other hand, her age might be correct and the infant may have died young.

Crockett is the son of Benjamin’s brother David.

1880 census of Floyd Co., Virginia, Indian Valley district, enumerated 15 June, lists on p. 31 as family #267/271:
Duncan, Benjamin, 60, farmer; Nancy, 50, wife; Julia A., 29, dau; Francina, 20, daui; Melina, 19, dau; Rebecca, 17, dau; Nanzella, 16, dau; Emazetta, 14, dau; Noah J., 13, son; John B., 11, son; Duncan, Crockett, 20, boarder. All born Va Va Va.