Why does all beer taste the same to me?

I've been 21 for about a month now and boy has it been one big disappointment after another. I like mixed drinks and coolers but I don't know about beer. In the past month I've taken sips of 6 different beers/ales- Rolling Rock, Leinenkugel's Sunset Wheat, Leinenkugel's Summer Shandy, Spotted Cow, Blue Moon, and New Castle. They all tasted awful and they all tasted the same. What's wrong with me? People talk about beer like it's ice cream or something.