This problem is solvable with detective work, but it is advanced genealogy First find the earliest possible record(s) for Robert Bratton--for instance where was he married (county and state and date). Then look for Brattons in that county and/or adjoining counties on the census closest to that date, and earlier. This would probably be the 1820, 1810, and 1800 census. Look up each Bratton family on the census and check to see if they they have a male child the age Robert would have been for that census year. Rule out all families that don't have a male child his age. Keep researching the other Bratton families. Places to look are census, tax lists (in the FamilySearch catalog), marriage records of other Brattons in the same county, land transactions (found in the deed records in the FamilySearch catalog), and wills of the elder Brattons. As you work out the relationships, you can often learn the answer. Of course, if there is only one Bratton family in the county during the time period of interest, and they have a male child the age Robert would have been, you are ahead of the game. I've used this method several times with my own family with success. Here is the FamilySearch catalog https://www.familysearch.org/search/catalog. First enter the state and then the county and it will take you to all of the record books.
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I found Robert Bratton in the 1860 Census on familysearch.org. family search is a free website, you just need to register to search.click on link below.
Also found a family tree..........https://www.familysearch.org/tree/pedigree/landscape/LHQ6-B1N
There is more information on family search
Good Luck in your search.