The book contains errors. We are trying to clean them up but:
The grave stone does not agree with the family bible.
The names and dates in the bible were written in well after the fact, and are the best recollection of who ever wrote them. We can't read their handwriting.
The ship's captain couldn't spell any better than ggggg---grandpa
"Standard Spelling" is a relatively recent invention.
The census worker couldn't spell and had really bad handwriting that day.
The newspaper misprinted the names and dates in the 'obit.
The courthouse burned down and/or was flooded, so the original records are not available.
Translation from old high German to modern English is not an exact science.
The church records were destroyed in the same fire/flood.
We have the person's name on four different documents and it is spelled 4 different ways.
Some information appears to have been altered or excised by little old ladies who's sensibilities were offended.
Military records are maintained by staff clerks who can neither write nor spell.
The ink has faded, and you wouldn't believe the stains on these documents.
Not every girl knows who the father was, or tells. The fathers are even less certain. We are going by the official family story until the DNA tests come back.
Mandatory reporting of births, deaths, and marriages is a relatively recent invention.
The entire census for this county was lost. (It was probably legible.)
Rather than research which John or Abraham was their ancestor, someone guessed.