I really did not understand what it had to do with the survey. On the face of it, it sounded like a total nonsequitur. There was no direct way I could relate rocks and snowballs to a survey.
So you're concerned that their study allegedly disregarded scientific principles and did not take a valid sample. I don't know about whether either was violated when making the survey, but I think it would be very difficult to get a valid sample of twins when one of the twins is gay. If more surveys are done, then a fusion of those surveys might well produce something that you would agree, is worthy.
Kinsey: As far as I know, he took his subjects from a prison. That would not make a valid sample.
Gore: I think that the earth might well be warming, somewhat, but due to natural causes, since most of the greenhouse gases come from natural sources.