The challenge with DNA testing as it relates to Sullivan Ballou is that he died in the Civil War, and his two children, Edgar and William, only had one child between them, Kathryn. Kathryn Ballou never had children and died in the 1920s, so he does not have any living descendants.
His grandfather (Ziba) and great-grandafther (Noah) each had several children though, so you could potentially find cousins from these Ballou relatives. There are many records on Ziba and Noah and their respective descendants.