Gender Fluidity
These days, our kids increasingly reject the boy-girl binary. Gender instead is seen on a spectrum. The metaphor out there of gender as Rubik's cube is also quite handy. Rather than two-sided (girl-boy) it has six different sides and each side has several rows and columns that can be morphed to create a side with an entirely new appearance. Each square, row, column, and side, with varying colors, is unique.
Gender identity and expression, as well as sexual orientation, often come into full swing in adolescence (though sometimes earlier too).
Gender is personal (how we see/experience ourselves), Sexual orientation is interpersonal (who we are physically, emotionally and/or romantically attracted to). Sometimes sexual orientation is described as who you sleep WITH; gender is who you go to sleep AS. Many people mix these up, but they are very different.
If you're confused, you're not alone. Check out the Gender Diversity page to see through the lens of today's teens.