I end up having two accounts. A female for my soullinker, high wiz and sinx who usualy ends up becoming the guild leader just because it's a fem character, then my male account for my more serious characters.
It's mostly based on my past experiences and the way other players treated me. When my female sinx was leader, the other people who we beat kept saying I would sleep with the admin or a gm to get my items when in reality I just took them away from my guildmates.

They also always assumed that the reason I was leader was because I had cloak, so they never bothered talking to me about alliances. Instead they'd talk to a co-leader, thinking they were the real brains in running a guild. =\
However, if my male sinx was leader, people would think I worked for my gear. They would send in a female character to talk to me about making an alliance, or funny enough, try to seduce me. But RO isnt as bad as WoW when it comes to the mistreatment of female sprites.