Do transgender challenge your view on gender?

Yes and no. The idea of transgenderism, that is, moving between or changing one's gender or sex is inherently against what most people think of sex and gender. However, I am genderqueer myself and was experiencing gender confusion and dysphoria before I learned what transgenderism was, so the concept wasn't too surprising to me when I learned of it. A lot of transgender people are against traditional gender roles (e.g. boys get trucks and girls get dolls, etc.) because they feel that it limited their experiences as children and forced them into a role that didn't fit them. Often it was their parents trying to enforce the roles. On the other hand, other transgender people act like "gender police"- they feel that the only way to prove that you are really transgender, really a man or woman, is to carefully follow and abide by gender roles. For example, if a transman (female-to-male transsexual) likes to crossdress (wear dresses and makeup, essentially), then he is not a "real" man.