Ok, a further thought occurs.
A while back I was playing a human cleric of Cuthbert. Real old Testament type, fire and brimstone. He believed that sinners should be cleansed by the fires of truth and proceeded to set fire to as many sinners as he could.
A few levels later, I took a level in Half Fire elemental because it really fit (IMO) with the character. He gained some fire immunity, could chuck some fire related spells and he looked like he was on fire most of the time. Kinda like Ghost Rider without the boniness.

I played it to the hilt. Really had a blast with the character.
After the campaign ended, one of the other players asked if my character was a genasi. I explained no, and what had happened.
So, did I fail my own criteria?
IMO, no, I didn't. There was no reason why my character would stop thinking of himself as human. He gained the abilities through a ritual (not the 4e kind - an RP kind) and his faith in his god. He was being rewarded for his fervor with a miracle. For all intents and purposes, he still thought of himself as human. He wasn't born this way at all.
But, on the other hand, no one at that table would think that I was just another human. They might not know exactly by the rules what I was, but, they knew something was up.
Sometimes, yes, there are perfectly good reasons why the other players at the table might not know the exact mechanics of your character. That's so not what I'm talking about. If there is a good reason for why the other players don't know something, that's fine. But, if the only reason is because the player is too lazy to actually play his or her character, then, that's poor roleplaying.
Fun or not fun doesn't enter into it. We're talking about quality of roleplay here. The quality of how well you portray your character. If the four or five other people have no idea what you are, for no reason than you just didn't bother putting any effort into it, then, IMNSHO, that's poor roleplaying.
Tycho portrays a great cleric. Fantastic. Piss poor half elf.
