I must dispute when Vintage said the Hero has to have royal bloodlines. In Kwaan's writings in the epigraphs of WoA, he mentions that Alendi was specifically not royal, but married a princess (essentially making him royal in that way). The prophecies said that the Hero wouldn't be royal.
Of course, since the Prophecies were manipulated, they could have said "originally" that the Hero was a royal, but that Ruin changed it to fit Alendi. So let's not look too far into those prophecies.
Changing subject!
Once again, I reference an annotation that says the Lord Ruler and Vin are powerful, but for different reasons. With the evidence provided in this topic thus far, such as the Lord Ruler soothing enormous masses of people but Vin cannot, but with Vin able to channel the mists, I can see that the Lord Ruler and Vin are actually quite different. I'm thinking that Brandon's entire thing about relating Vin to the Lord Ruler and the Hero was all just subtle deception. I'll say it again: Vin and the Lord Ruler are different. Somehow.
Part of the Lord Ruler's power comes from Feruchemy, and then some other things we don't know about. It could be something relating to Hemalurgy (before anyone disputes this, I believe I have explained my opinion that the Lord Ruler does use Hemalurgy in the Hemalurgy topic), or something else entirely.
Vin channels the mists. I'm almost wondering if the Lord Ruler could also use the mists in such a fashion. But, then, if the Lord Ruler had that ability, he certainly would know its extent, and would know if Vin could defeat him by taking off his bracers. Maybe he didn't know anyone else could use it...
Maybe that subject should go in the mists topic.
Last thing, I doubt the Lord ruler would've procreated. He made the Terris breeding programs specifically to remove Feruchemy. Since Feruchemy and Allomancy are both heriditary, any child of the Lord Ruler would have the exact same abilities. The Lord Ruler fears a powerful challenger to his authority, so I'm absolutely certain he wouldn't have kids.