I brought Sakura to Codex about a month after I joined, mostly because she was tired of me telling her stories about what happened here. So she joined herself.
We are MARRIED. We have sex on a regular basis and we are allowed to because God says it is okay to have sex as a married couple. If that grosses you out, I'm sorry. We had to have a daughter somehow.
We are not brother and sister. That would be gross.
I hope this clears everything up for those didn't know and for those who weren't paying attention.