Are you paying me to work or are you paying me to socialize?

So Thursday just before I left work, my boss called me into her office and had me close the door.

Apparently, all of my co-workers find me to be "unfriendly" and that I always "have a pissed off look on [my] face." And that when other people walk in the door and say "good morning" I don't always pick my head up and chat with them. And since I'm the new employee and everyone else has worked together for over 10 years, I need to either gel with the clique or find work elsewhere.

When I was in her office I was very apologetic and assured her that my behavior would change and I would try my best to interact with everyone else in a friendly manner.

As soon as I got home, I updated my resume and began sending it out for various job openings.

I understand the need for a positive work environment, but I have never felt fully welcome working in my current office. It was obvious to me from the very first day that they thought I was just going to be temporary and then when I asked them about it it seemed like they begrudgingly made me a permanent position. One of the bosses has never been all that nice to me at all to be quite honest. I feel that because I am 20+ years younger than everyone else, they treat me as they would a child or a teenager. It infuriates me at times but I don't complain. Because why cause a problem over a minor thing? I keep my head down and do my work to the best of my ability which is apparently very well since I am consistently praised for it.

So why is it such a problem when I don't stand by the water cooler and chat with people about television shows I don't watch or sports teams I don't like or tell them how all I did this weekend was work my other job and play video games? Or read comics?

Don't get me wrong--the office atmosphere is very relaxed and I like hearing their conversations and stories and listening them joke around with each other. But I have found several times when I have tried to participate, the conversation seemed to just end right away. So how do I socialize with people who have made it somewhat clear that they don't wish to socialize with me? I tried bringing this up to my boss and she just looked at me like I had 3 heads. Of course it's my fault--I'm the new girl. I'm so-and-so's daughter.
My question is: are you paying me to socialize or are you paying me to do my job? Because I've been doing my job and seeing as how I haven't yelled at or cursed at anyone in the office, I don't see why me being "the quiet one" is a problem.

I think a trip to Wal Mart tomorrow is in order. I'm just going to buy the biggest, most obnoxious headphones I can find and keep them in my desk. Then I'll just wear them all day so people will know that I'm not ignoring them, I'm just doing my damn job and listening to music at the same time.

Hopefully at some point soon, I will get a job elsewhere so I don't have to deal with this.