I always play the "what would it change if I learned ____" game with this kind of thing.
I predict outcomes from most to least likely and then mentally assess what, if anything, those outcomes would translate into in my family's lives in particular.
Sometimes that means testing-- and sometimes it means that NOT knowing (if there's little that it would change, or if an ambiguous result would lead to a series of dissonances that would be hard to tolerate).
I never believe in "just because" testing. I learned that lesson the hard way with our DD (not with GT stuff, but with other stuff).
