Though it's of little help to Don's problem, well that and we've managed to sucessfully hijack his thread I'll add in one simple fact that will clarify things compeltely.

If you are toting around that Y chromosome, to anyone else you will always be wrong, unless that person too is a Y carrier in which case you stand a 50/50 shot of being right with proof and beer. The presense of the latter will generally give more weight and help validate the former.