The reasons for why you are attracted to the people you are attracted to come down to 3 main things: proximity, similarity, and physical attractiveness. In reference to proximity, we like people who are physically close to us. You see them more often and talk to them more; they are familiar to you, creating attraction. Similarity is a big factor which brings people together, such as having things in common. Opposites, surprisingly, do not attract. Physical attractiveness is also a big part in attraction. From birth, more attractive babies are even perceived in a more positive way. Many studies have been done to support these ideas, some of which are described in this article below.
Why We Like Who We Like