I am a descendent of John Abraham, born 1840 in Butler Co OH, brother of your Lot Abraham. It is a confusing family because every generation has a John and a Lot in it. According to personal information I received from a family member, the father of these men was also John Abraham, born 2-10-1806. He married Sarah McCue 11-25-1828. He died in 1843 in Mt Pleasant IA, shortly after the family moved from Ohio. This correlates with your info that you found Sarah and the children in the 1850 census in IA. It also correlates with Herbert Abrams' suggestion that John Abraham was born in 1806 and fits the family in the 1820 census from Butler Co OH. There is a discrepancy with the personal info I have, which I have not researched. According to the info I was given, his father's name was Lot Abraham, born 1765 in Butler Co OH. This is off from the info in the familysearch database, which lists his birth year as 1775 and place as Chester Co PA.