It may be possible to confirm family relationships with Joab by comparing test results with other carriers of his Y-chromosome or his mother's mitochondrial DNA.
However, there are no known yDNA or mtDNA test-takers in his direct paternal or maternal line.
It is likely that these autosomal DNA test-takers will share DNA with Joab:
My name is on this profile due to a merge. I do NOT think we have enough information to say who Joab's father was. I also do NOT think that Winnifred was his sister. I do think that John Mauldin who died 1832 in Pendleton, SC, was his brother. See http://www.wikitree.com/wiki/Mauldin-405