My brother's ex girlfriend had a baby and my brother refused the paternity test because he's a dumbass who thinks if he doesn't take a paternity test, she can't come after him for child support. I didn't know anything about legal stuff but I offered her my DNA to test for a familial match. She very nicely told me she doesn't need it and the court will compel the test, but somehow my brother and my father found out and they're really pissed at me for "betraying the family" and "trying to fuck my brother over." AITA?