There are huge psychological factors at play here and as much as I hope fervently the boys will be able to "find out what really happened" I'm not terribly optimistic given the mother and grandmother that have been indoctrinating them for years. I ran across
this article discussing OJ's kids and whether they believe he is guilty of killing their mom. The evidence of the Juice's guilt is so overwhelming (hello Bruno Magli shoes). Nevertheless, it appears both older kids firmly believe in their father's innocence and if Sydney's ex-boyfriend is to be believed, she doesn't accept his guilt either.
I personally went through a bitter divorce with a young son whose mother did a number of truly despicable things hoping to turn him against me. He was under enormous pressure and eventually took his own life leaving a note that broke my heart. It gave me an appreciation of how much a mother can screw up a child. Unless the boys break away from their mother/grandmother emotionally, I expect the facts and evidence will be much less important to them than maintaining the approval and affection of WA and DA.