Gender
From Alter Aeon Wiki
Mobs and player characters can be one of three genders: male, female or neuter, the first two genders can be chosen from the new character creation screen, the third option requires drinking a change sex potion. Picking a gender makes very little difference to playing other than there is a slight change in some of the strings sent to the rooms and some of the msp sounds will be different.
Change of sex potions
Gender can be changed by using the sexchange male and sexchange female spells which are usually found on potions like the change of sex potions that are sold by the magic shopkeeper in the City of Ralnoth.