Are you a Lesbian?

People write to me all the time looking for the answer to the question: Am I a Lesbian? Recently I heard from a 19 year old college student who is attracted to another girl in her class. This girl happens to be a lesbian. Is it possible to have an attraction to a lesbian and still be straight? Or does it make you automatically bisexual or lesbian? Here is the advice I have to offer to anyone asking the question: Am I a lesbian?