When talking about somebody's lineage, it's best to remember, that the last of the line, at least at that present moment, is not the ancestor of that line. (Barring, of course, time travel) That person, instead, is the descendant of whatever people, line, king, etc. Please remember this. It's not that hard. Especially when you used the phrase 'descended from' in an earlier sentence.
And on a more fanfiction specific note, I would just like to mention that it is possible for people who aren't your main couple to be straight. I mean, if you want to just make your story just one big gay orgy, that's fine. But if you say your story is realistic, and not one character out of a couple dozen in your fic is even interested in the opposite gender, at that point I may have to just disagree with it being 'realistic'.
Just so you know, it's possible for homosexuals to appreciate the form of the opposite gender. It doesn't mean it necessarily turns them on, but they can at least acknowledge if someone is pretty/beautiful/handsome etc. Same thing goes with straight people and their own gender.





