After learning about some rather interesting philosophical concepts, I came up with what I think is an interesting fan theory.
I can't remember if it's Plato or Aristotle who came up with it, but one of them suggested that humans should be bred like we breed dogs, those with the better genes and the capacity to lead being put into buildings with little material possessions or something like that, I basically have this philosophy soup floating around in my head so I barely remember much of anything from those classes.
Anyway, the idea of breeding humans feeds into my Castlevania headcanon. That headcanon?
Right after the events of Lament of Innocence, the Belmont family has been breeding progressively better and better monster hunters and vampire killers. Leon specifically picked out his wife(or next wife, since I think Leon's a widower, I couldn't figure out the controls for Innocence so I was like NOOOOOPE) in order to ensure his child would be a better vampire killer.
This keeps on going with each generation specifically breeding to make better, stronger, more powerful and, as a side-effect they weren't even trying for, more attractive Belmonts.
Occasionally, they resort to linebreeding in order to keep traits in the family(linebreeding is where you breed cousins with each other) or because special blood is difficult to come by. As a result, every single non-Belmont character we see in the games who allies with the PC likely winds up in the Belmont family in some form, usually because they marry in or have kids with the PC. Hell, considering that I think a couple Belmonts can summon familiars and/or use magic, maybe Alucard himself decided to inject his own DNA into their family at some point.
At some point, around the time of Order of Ecclesia, the Belmont family's reached that point where they can't find anyone to get into their family who can help further the vampire hunter part they've been trying for and, as a result, you have a bunch of duds in the form of the villagers you rescue throughout the game: some have powers, usually things that won't help in the long run, but most don't.
Enter Shanoa. After slaying Dracula, she decides to give the Belmont family a MASSIVE genetic boost by getting into the family herself, resulting in a power surge in the next Belmont.
Eventually Aria of Sorrow rolls around, set in 2036, we see what the Belmont family has created so far: Julius Belmont, who is the strongest member of the Belmont family next to Harmony of Dissonance's protagonist Juste, who's right after Julius.
My headcanon involving Julius is that, because of all that careful breeding his family has done, not only is he the strongest Belmont in the main timeline, he's also the longest lived, losing the ability to bear children at a much later date. He's only fifty-four when Aria rolls around, so as long as he can get it up, he's able to make another Belmont.
So yeah, long story short, the Belmont family tree has one massive main branch and about eight gazillion smaller ones they occasionally use to breed in traits. It's pretty much a happy accident that they keep coming out so good looking.
_________________
The autistic should run America. Chances are they'd do it better than the NTs.