Doesn't the pregnancy of Sarah Palin's daughter prove that teaching abstinence doesn't work...?

... since presumably she was taught it, and she still got pregnant before marriage. (note that I said "teaching abstinence", not "practicing abstinence", which obviously works!) Conservative claim that if you teach "abstinence only" to kids, they will actually abstain, but I would argue that this opinion is refuted by the actual behavior of the kids, which is to keep on having !