I think the 'opposite theory' works on AVERAGES thus you would expect there to be some individual variation (where some people don't exhibit that).

I didn't know (or remember) the stuff about HLA so thanks for that :-)

I thought that pheremones just were responsible for our unique scents. Is it that pheremones are one distinct aspect of that such that people think that the girls were choosing on the basis of some other aspect of scent?

Thinking more on the similarity / difference thing... I wonder if people who have 'distinctive' characteristics would show preference for differences... I just mean... When I said that I preferred guys who were like a male version of me... I just meant that with respect to body type. I'm fairly tall (5'7 or 5'9 I can never quite remember) and fairly solidly built. I tend to be attracted to guys who are a bit taller than me and as solid (or preferably slightly more solid) than me. I also have dark hair and I think I prefer dark hair though that is a whole heap less important to me lol.