This is your problem - you not located the parents in the census records - Facts you should know about the early census records –
All census records [1790 – 1840] prior to the 1850 census ONLY listed the head of household; whether male or female.
NO specific age was stated for any family member NO place of birth was stated – city, state, or country NO city, town, or village is stated – only the county; however some census takers listed the township NO street address was stated NO marital status was stated – single, married, widowed, or divorced NO family relationship was stated – brother, sister, cousin, son, daughter, wife, inlaw, etc… NO occupation was stated NO parental birthplaces are stated NO race was stated [but assume “white”]
1850, 1860 & 1870 census records do not show family relationships, marital status or parental birthplaces.
Step children are not enumerated as “step” children Adopted children are not enumerated as “adopted” Grand children are not enumerated as “grand children” Orphaned children were not enumerated as "orphan"
1850 is the 1st census that shows all family members
1880 is the 1st census that shows parental birthplaces and family relationships +++
1880 - Neither Isaac nor Arthena [STITES] Thomas are listed on this IND. census
1850 - Name: Isaac Thomas Age: 32 Birth Year: abt 1818 Birthplace: Kentucky Home in 1850: Greencastle, Putnam, Indiana Gender: Male
Isaac Thomas 32, KY - farmer Arethinia Thomas 33, KY Samuel Thomas 6, IND Carlisle Thomas 3, IND Aaron Thomas 2, IND William Thomas 12, IND
1860 - Name: Isaac Thomas Age in 1860: 42 Birth Year: abt 1818 Birthplace: Kentucky Home in 1860: Madison, Putnam, Indiana Gender: Male Post Office: Greencastle
Isaac Thomas 42, KY - farmer; appears to be widowed Samuel T Thomas 15, IND Harrisson Thomas 13, IND Aaron H Thomas 12, IND Wm C Thomas 11, IND Jacob Thomas 10, IND Frances E Thomas 8, IND Geo W Thomas 7, IND Lewis A Thomas 4, IND