When you actually stop and think about a blood descent from a royal or noble ancestry, you also have to look at the history. Back then too, the mores of sexual relationships weren't as they are now. It was a time when brothers married half sisters and had concubines and sex was not free again until sex, drugs and rock n' roll ruled n the 60s and 70s. Monogamous relationships weren't the norm. Who survived and who didn't depended on that. Then we have the great purge which wiped a lot of us out in the Middle Ages.
We're talking back to the times from Alexander the Great who died in 323 CE. He could have had multiple offspring but... think about it.... how many may have died in the years following due to poor health, famine and the ultimate destroyer.. the plague through the centuries of the Middle Ages.
I'll put my descent from the Anunnaki as a priority before Alexander.