I'm not 100% sure I know what you're asking here, but as long as the roleplay abides by the Site Rules, it should be just fine.
There are plenty of people that enjoy incestuous plots such as father/daughter characters, but the big one here is to make sure that there are no characters below the age of 15, as per site rules. As long as the RP is rules compliant, you and your partner's imagination is the only limit.