Doctor George did a cursory tabulation of the gender make-up for the 2008-2009 academic year of his undergraduate psychology courses and he found that about 80% of the students were female. As for the remaining 20%, it is unlikely true that all of them are gay. For instance, Doctor George, is a psychologist, and thus a former psychology student, and is married and not gay.
That said, the statistics are not the problem. If you are concerned about being labeled a certain way, and if you burden yourself with stereotypes, you will find yourself defending your choices no matter what you do and no matter what the reality may be.
By its very nature, psychology is a subject that requires us to examine ourselves and our world views. It includes exploring how we acquired those views through our early family relationships. Unlike most areas of study, in psychology, we, the student, are an integral part of the subject that we study. This self-examination can be a heroic quest, sometimes including personal therapy and eventually leading to a career. When you decide to embark on this journey of self-exploration, it's likely, and frankly desirable, that some of your currently held views of life will change. In fact, that's desirable for all study, no matter the subject or when we are studying it.
Whether or not some, most, or all male psychology students are, gay, you need to decide whether your affinity for the study of psychology is greater than your aversion to being associted with women and potentially gay men. You need to ask whether you would like to only be with people who are just like you, or whether you would you like to know people who are different. In other words, would you like broaden your views or stick with the ones you already have? Would you like to pursue your dream -- if it is a dream -- or have your life's actions dictated by what other people might or might not think?
We all have fears of various types and degrees when we are embarking upon a new venture. In his The Hero With a Thousand Faces, Joseph Campbell describes the first stage of the hero's journey as going beyond the boundaries of the community, a journey into the wilderness. This entering into the unknown is a feared action that takes us outside of the protection of our ordinary world and exposes us to unknown dangers. In myths worldwide, it is represented by the hero's being attacked by beasts. On ancient maps uncharted geographical areas were labeled Hic abundant Leones ("Here there are many lions."). The unknown was automatically considered bad. In the case of entering a university, and becoming a psychology major, one of the "beasts" is the fear of encountering people who are different than ourselves. When we are grounded in who we are, we have no fear of encountering other views. That leaves us free to explore. On the other hand, when we are afraid of who we are, we have to protect ourselves from exposure.
These are some of the fundamentals of psychology. The better you are at asking these questions for and of yourself, the better you will be as a psychologist.
As obvious as it may seem, in whatever we choose to do in life, it is always important to ask ourselves what we are trying to accomplish. The question is whether we trying to learn and grow and allow ourselves to evolve to our fullest potential as human beings. As Norman Mailer said, "That was the law of life, so cruel and so just, that one must grow or else pay more for remaining the same."