How do we shape our gender identity?

I wake up in the morning, take a shower, get dressed, and head out the door.  Most of the time, I eat breakfast in the car, get coffee on my hour long drive to school/work, and put make up on when I get there.  Sometimes I shave my legs, sometimes I don't - it depends on how healthy they look.  About every two to three days I will shampoo and condition my hair and shave my arm pits.  Today, I ask myself, who taught me to do these things?  How did I learn that for me to still feel feminine, I have to shave my arm pits at least every three days?  If my legs were healthier, I would probably shave them more often, but why?  It is hard to imagine my routine any different because it is edged in stone. I'd like to say that my routine has formed because I have established a way for me to feel comfortable in my skin and it complies with my personal needs.  Can that really be true?  My fear is that most of my habits are shaped from the media and from my social networks that I have had over the years.  In fourth grade, I was the only girl not shaving my legs.  The decision to shave my legs was not my own, it was a mixture of what I thought was feminine-ly correct through tv and advertisements as well as what my mother felt was best for me as an individual, a girl, and her child.  When I was in seventh grade, I learned that I was not a little girl.  I don't mean age or height.  I was overweight and nicknames would begin that would follow me through my first years of college.  Media was showing me and my peers that you had to have hairless legs and armpits (or any unattractive hair such as a female mustache should be handled carefully) and that beauty was the most important thing about who you were.  But what is beauty really?  There were heavy girls that were popular.  Some popular girls wore make up - some didn't.  Some popular girls had frizzy/curly hair - some didn't.  At a young age I learned that it didn't really matter what you looked like - instead you just had to make sure you didn't have too many strikes against you.  It didn't matter that I was a little overweight.  What did matter was that I was slightly overweight, had frizzy hair, glasses, acne, and didn't wear makeup.  Media dictates the ideals for each of these categories and if you don't comply, then you are subject to ridicule.  What makes it worse is that these ideals are passed down from many angles and you can't shield anyone from everything.  Girls figure out what is 'sexy' by watching tv, playing with other children, searching on the internet, judging their peers or being judged by their peers, participating in gender norms with their mothers, paying attention to their female teachers, noticing which adult women are considered attractive by other adults, and so much more.  Young girls are often oblivious to how much they are taking in about what it means to be a woman and to be sexy.  My question today, is how do you shape your identity, how does it shape you, and how does it shape our children?