I get the impression (maybe because JK has older daughters then IIRC a son) that he really really doesn't like teenage boys .
Scenario: young lady , has baby , doesn't know who the father is.
DNA test for Potential Dads.
"If it's Mike he's got to step up" "If it's Dave I don;t want him anywhere near my baby" " I hope its Martin, he's more of a Dad than he'll ever be"
JK asks "Who do you want it to be"? like there's a choice . The father IS who the father IS.
And once the identity is known he spits " Of COURSE you're the childs father" ............ so if you're all so sure , why the DNA?
I don't care if she's fucked the entire football team and the manager , but the 'guests' can't decide who the Dad it , it's biology not wishful thinking 
And when they sit there wagging their leg , JK should slap them on the shin.
No I haven't been on it , but if I lived nearer to the studio.....................