From the Ragnarok Online site:
"To avoid role play related complications and conflicts, we do not support users playing characters of a different gender. Please be aware that the iRO GM Team cannot offer to correct the gender of characters for users that have entered the incorrect gender, either intentionally or by accident, during the account registration. Although we have offered account gender corrections in the past, this is no longer possible due to recent updates to the iRO game. Thank you for your cooperation."