Very Confused on Parentage of Nancy (Byers) Chamberlain b. 1851 d. 1931

I have been tracing the life of my great-great-great grandmother Nancy Byers, born in 1851 in Ohio. The first record I have of her is the 1860 us census, which states the following:

Name: Nancy J Byeres [Nancy J Byers]

Age: 9

Birth Year: abt 1851

Gender: Female

Birth Place: Ohio

Home in 1860: Center, Noble, Ohio

Post Office: Sarahsville

Family Number: 922

Value of real estate: View image

John J Byeres 61 Elisabeth Byeres 42 Margaret Byeres 20 Mary Byeres 18 William Byeres 17 David Byeres 14 George Byeres 14 Elisabeth Byeres 11 Nancy J Byeres 9 Joseph Byeres 7 Robert Byeres 1

You see my problem? At first I thought John Byers and Elizabeth Byers were Nancy's parents But then I realized John is 61, and Elizabeth is 41! Twenty years difference. So I did more digging, and came across Nancy's death certificate:

Name: Nancy Bell Chamberlain [Nancy Bell Byers]

Death Date: 7 Apr 1931

Death Place: Salt Lake City, Salt Lake, Utah

Gender: Female

Age: 79

Marital Status: Married

Race: White

Birth Date: 23 Sep 1851

Birth Place: Portsmouth, Ohio

Father's name: John Byers

Mother's name: Mary Jones

Spouse's Name: Noyes Chamberlain

Document Type: Certificate of Death

See?! John Byers and a Mary Jones are obviously Nancy's parents. Not even close! A marriage record of Nancy's brother Joseph, states his parentage as John Byers and Elizabeth Botty! Lets jump ahead to the 1870 census:

Name: Nancy I Byers

Age in 1870: 18

Birth Year: abt 1852

Birthplace: Ohio

Home in 1870: Railroad, Starke, Indiana

Race: White

Gender: Female

Post Office: San Pierre

Value of real estate: View image

John Byers 71 Elizabeth Byers 52 Mary Byers 26 Elizabeth A Byers 20 Nancy I Byers 18 Joseph A Byers 16 Robert Byers 11 Sarah J Byers 9 Rosella Byers 2

No new clues! Who is actually Nancy's parents? Am I confusing 2 different people? According to the death certificate, the person who stated the parents of Nancy was Nancy's daughter. Coincidently, Nancy's husband Noyes mother was a Mary Chamberlain.

Could the daughter be confused? Twenty years apart marriage? Wrong family? Please help!

EDIT: Mary Jones is confirmed to be the mother of Noyes Chamberlain. Who is the real mother of Nancy?