The first set of twins is said to be born 10 Mar 1772, but our subjects were not yet married then.  The census shows Nancy's birth in 1874, which makes more sense.

1.  LDS.  Family Search: Internet Genealogy Service:  IGI - International Genealogical Index (online at FamilySearch.org).

Joseph V. BENSON Spouse: Elizabeth GOFF Marriage: 23 May 1872, Preston, West Virginia Husband Age at Marriage: 30 Wife Age at Marriage: 24 Source: patron submission

Joseph should be 40, not 30.  If Elizabeth's age is correct here, then she's fibbing about her age in the 1880 census.

2.  1860 Census Index/Images (online at Genealogy.com; Image #1 of 1):  Post Office at Guseman's Store, Brandonvile [near Bruceton Mills], District No. 2, Preston Co., VA [now WV], Roll 1372 (Book 1), p. 74, 491/483, enumerated 11 Jul 1860, official enumeration date 1 Jun 1860 (extracted by Diana Gale Matthiesen):

Kesiah Benson	70	F					Va
John      "	30	M		Farmer	400	183	"
Joseph    "	24	M		Farmer	400	183	"
Cecilia   "	26	F					"
Marcellus "	6	M					"
Allen     "	4	M					"

The ages in this census do not jibe well with those in other censuses.  Keziah is Joseph's mother; John and Cecilia are Joseph's siblings.  Marcellus and Allen are almost certainly Keziah's grandchildren.  The fact that John and Joseph have equal amounts of property suggests that they just came into an inheritance, which jibes with the fact that their father died in 1859.

3.  1870 Census Index/Images (online at Genealogy.com, Image #16 of 40):  Rowlesburg P.O., Pleasant Twp., Preston Co., WV, Roll 1697 (Book 1), p. 140B, PN 16, 106/106, enumerated 30 Sep 1870, official enumeration date 1 Jun 1870 (extracted by Diana Gale Matthiesen):, official enumeration date 1 Jun 1870 (extracted by Diana Gale Matthiesen):

Benson Joseph ?	37	M	W	Farmer	700	300	Virginia
______ Caseah	75	F	W	Keeping House			Virginia
______ William A	16	M	W	Farm Laborer			Virginia

I can't read Joseph's middle initial.  "Caseah" (Keziah) is Joseph's mother.  William is presumably one of Keziah's grandchildren.  Living next to Joseph's brother, James BENSON. 

4.  1880 Census Images (online at Ancestry.com, Image #8 of 37 — indexed "Joseph M. Benson"):  Pleasant District, Preston Co., WV, p. 245D, PN 8, SD 1, ED 59, enumerated 7 Jun 1880, official enumeration date 1 Jun 1880 (extracted by Diana Gale Matthiesen):, official enumeration date 1 Jun 1880 (extracted by Diana Gale Matthiesen):

1880:  for an explanation of the column headings, please see What the Numbers in the Federal Census Mean (missing columns contained no data).

1

2

3

4

5

6

7

8

9

10

13

16

22

23

24

25

26

67

67

Benson Joseph N

W

M

48

/

Farmer

WV

WV

WV

______ Elizabeth

W

F

30

Wife

/

Keeping House

/

WV

WV

WV

______ Nancy J

W

F

6

Dau

/

X

X

WV

WV

WV

______ Martha A

W

F

4

Dau

/

X

X

WV

WV

WV

______ Mary C

W

F

3/12

Feb

Dau

/

X

X

WV

WV

WV

______ George H

W

M

3/12

Feb

Son

/

X

X

WV

WV

WV

Goff George

W

M

34

Brother-in-law

/

/

/

/

WV

WV

WV

There is something written (one tiny word) above Martha's name that I cannot decipher.  Living next to Joseph's brother, James BENSON.