Skewed poll results. Probably conducted in California. If conducted in San Francsco it would only be 2 % opposed.
(1) You call 1,000 people on a poll these days and PEW reports that you'll end up with only 90 responses. That's when
(2) happens. There, a small group, let's say GBLTs, pass the word and agree that no matter what they will answer all calls from pollsters. The result is
(3) Each GBLT is answering at a rate 11 times as high as the normal/average person included in the survey. That would mean that out of 100 responses, you'd a few more gays answering than straights.
This is, BTW, exactly why Romney's people thought he was winning ~ they believed the Gallup polls ~ which were not 'normalized'