dna-same mother

[rachelsdad]

if there were 2 brothers who suspected they had different fathers but shared the same mother-how far would dna tests prove this ?

unfortunately,one of the fathers died

[bernardo]

Yes - it could prove it. A test between A and B can prove that A is the father of B, or not related. If C and D think that they have different fathers, then testing the father who is still alive will be able to prove whose father he is.