I still don't care for that. LoS, it doesn't matter. That game is it's own thing. But the original canon, I was always more interested in the family feud thing. To me, I like the idea that the Belmonts and Dracula's connection ISN'T blood relation, but something different. Maybe even something personal(with out reverting to the basic Maury DNA test as being the answer). I have more facination with two feuding families, fighting for good and evil, and the Belmonts just happen to be super human(because there can be other powerful beings in the world that don't draw their power from Dracula).
Besides, it makes more sense, even with Legends, that the Belmonts are just born from a badass family considering Sonia's not a descendant of Alucard or Dracula, and she still kicks ass(she's able to defeat Dracula). One could obviously think that Sonia inherited her parents' prowess, and so on, generations before her. It's just a badass family, in general. And yeah, being descended from Dracula proves NOTHING because of Sonia herself. She's a testament to that.