The thread doesn't really claim that introverts can't be sexy. Just because sexy people are likely (hypothetically) to be extroverts doesn't mean introverts can't be sexy as well. Your logic is made of fail.
Maybe cognitive function extroversion is determined long before puberty, but some people are shy as kids and outgoing as adults. This is quite common actually.
I was quite outgoing and lively as a child, but now I'm rather private and reserved. Maybe it has to do with something I experienced during puberty which I think plays a large role in the development of congitive functions. But once agian, I'd be extremely careful to equate introversion with shyness. I would argue that there is a correlation, but I think Sky described it quite nicely - not every introvert is necessarily shy, and I'm quite sure that there are shy extraverts as well.
I think it's a confusion of introversion/extraversion in common use and the specific meaning they have in the typological/Jungian sense. The former definitely equates introversion with shyness sometimes; the latter doesn't.
Perhaps physical beauty is a function of one's ability to take care of their body, skin, hair, and general physical upkeep. Extroverts may have more of a reason to keep their body in ship-shape since more people see it. Perhaps the thread should be more like "If you're an extrovert, are you more likely to be sexy?" I don't know; I'll have to think about that one.
Honestly, this whole thread is completely non-falsifiable. I just wanted to think about the possible correlation.
I'm very careful about my appearance. I'm definitely not the person to say that "appearance doesn't matter" because it's as much a part of me as anything else. I see it as a possibilty to present myself in a certain way. I don't think I'm superficial for that reason; I simply think it's a fact that people look at me and will judge me accordingly.
As to falsifiability, well - I doubt that sexyness is an objective category. There is certainly a general perception of what is considered "sexy", but I'd say this is rather the majority of subjective opinions. - There's no way to convince one person of another person's attractiveness.
It's not my personal preference, but just a summary of the plot of half the teen movies made.
I didn't mean to imply that. On a more general note, I'm slightly annoyed by things like beauty pageants (and ads, films etc.) because they seem to imply that there is something like objective beauty. I don't know how much of an impact they have; all I can't say that I probably wouldn't want to date most of the women that are generally considered attractive (based on their appearance).
