Ryan Evans is the very fashionable fraternal twin of Sharpay. He was chosen by Julliard School to take scholarship because of his choreography in the Senior Year Spring Musical.
There is no definite proof of Ryan's sexuality, however his flamboyant fashion choices, incredible dancing capabilities, and his interesting interactive showdown with Troy Bolton's best friend Chad Danforth in "I Don't Dance," seem to point to Ryan being of homosexual nature. It is to be noted that, while he is said to have a "crush" on Gabriella Montez, but noticeably reacts in the manner of a school girl whenever Troy enters the vicinity. During his Senior Year, Ryan is seen wearing more obviously flamboyant clothing than in the other two years. When everyone is hugging during "Just Wanna Be With You", Troy and Ryan twirl each other around, possibly imitating their rehearsal. His relationship with Kelsi Nielson is rumored to be an example of him being heterosexual. Interestingly enough, after asking her to prom, he never speaks to her again. And while at Troy's party, he and the basketball star trade lines of a flirtatious nature, sharing several more scenes that implicate things...
But the relationship between Ryan and Kelsi started from the first episode and cycled through all three. He thinks of course they would go to prom together and he still doesn’t think that that makes him gay or straight or anything. He needs someone to be a couple with; he’s not going to be with his sister because that’s gross.
After definitely taking notice of Ryan's flamboyancy, in the end, whether Ryan is straight or not is left up to the viewer's interpretation.
However, Ryan could also be metrosexual.