Bob Yougotancestor and Tom Yougotancestor have DNA tests done on their paternal line. It shows no paternal connection. So their supposed Yougotancestor lines are not related. Maybe.
Here's Bob's lineage:
Thomas Yougotancestor, father of:
George Yougotancestor, father of:
Henry Yougotancestor, father of:
Michael Yougotancestor, father of:
Frank Yougotancestor, father of:
Here is Tom's lineage:
Elam Yougotancestor, father of:
Abraham Yougotancestor, father of:
Ulysses Yougotancestor, father of:
Vincent Yougotancestor, father of:
Archibald Yougotancestor, father of:
It is thought that Elam and Thomas Yougotancestor are brothers or first cousins--and further work needs to be done to make the connection. Paternal DNA tests indicate Bob and Tom have no connection via the paternal line. Researchers conclude that Elam and Thomas are NOT related. This conclusion may NOT be correct.
Elam and Thomas may still be related.
What if the real problem is that when George was away in the military his wife was friendly with a neighbor and son Henry is not really George's son? This would cause Bob and Tom to not have a direct male connection, but Elam and Thomas could still have been brothers or related in some other paternal way.
The DNA evidence fails because George Yougotancestor was not Henry Yougotancestor's son, not because Elam and Thomas were unrelated.
Just something to think about.
Paper records may contain errors. DNA may also be inconclusive. What is worth remembering is that no tool is foolproof. The problem I have with DNA for genealogy is that it tends to be hyped more than necessary and pitched as a cureall. I'm not opposed to using it, but like any tool it must be used with care.
The hammer is not the problem. It is the human on the end of it that causes problems.