Remember that thread along the lines of women should be married by 35 or something like that? Views like that are nationwide and worldwide, so society's almost arbitrary or at least outdated standards about women are why, in addition to the extreme importance society places on youth and beauty....
My mom got HEATED when I was like 12 and asked how old she was....she was livid, and said 'Let me tell you something that is NONE of your business, and NEVER ask a women her age' lol I still rarely ask age, just when they graduated to get an idea...