The DNA couldn't have been JBR's. It is from a male. BUT she could have picked it up on her own hands touching pretty much ANYTHING that day- how many men and boys were at the White's? And then transferred to her longjohns herself, in the act of pulling them up and down.
I think most people recognize that, mostly because of her brother's testimony and the pineapple in her stomach that she was indeed awake at some point after the arrived home from the White's.
So it wasn't just a matter of someone else pulling them up and down.
Just suppose it had belonged to some innocent guest at the party and JBR picked it up touching a doorknob. THEN along comes Lacy and her parade of clowns at the DA's office and LOOK! WE HAVE THE KILLER'S DNA PROFILE! Some poor guest- someone's father, someone's husband- gets sold down the river because the Rs are too gutless to step forward and the DA's office too scared of the R lawyers so they railroad the guy right into a life sentence. Case closed!
This was perhaps even more irresponsible and dangerous than the Karr circus.
This DNA clears no one. It doesn't mean they didn't commit this crime and/or the coverup. All it does is prove that there is male DNA on her CLOTHES that doesn't belong to an IMMEDIATE family member- and that's it.