Subject: Whatīs the problems with twin-studies to dicide upbringing vs genes?

Iīve heard that genetics arenīt really pleased with the results thatīs being 
rapported when it comes to the comparison of personalities and between heritage 
vs upbringing. They think itīs to biased in favore of the upbringing.
What I understand itīs two major complaint: 1. The personality-tests arenīt that 
precise. THIS I donīt understand, I mean if they are not it could just as much 
be in favor of upbringing, or.... And 2. It isnīt the environmental cues that 
the upbringing-people think (itīs much more subtle events that influence).
Please explain number 1. And perhaps you have even more arguments against 
upbringing??!!!!!!!!!!!!!

Re: Whatīs the problems with twin-studies to dicide upbringing vs genes?