It may be possible to confirm family relationships with William 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 William:
No other area of WikiTree insists on specific source statements, layouts or similar and as genealogists we are expected to check details of any nature for ourselves.
There are links given in the yDNA section where anyone curious about the confirmation can check the data for themselves.
Why do we have to spoonfeed this aspect of WikiTree but not others?
Paternal relationship is confirmed through Y-chromosome DNA testing. Anonymous Roberts and Peter J. Roberts match on 36 out of 37 markers (see YSearch IDs 9WCMS and 97ZDB) thereby confirming their direct paternal lines back to their MRCA Thomas W. Roberts.