They are ignoring - but not really outright making a point of directly contradicting...if they wanted to do that, they wouldn't have *twice* acknowledged the 8th Doctor a canon.
Personally, I love the idea of the Doctor being 1/2 human because it explains his fondness for Earth - and the UK - and his various Brit accents...
His mother was a British human?
That's something I took from "The Empty Child" two-parter. The Doctor sounded like he really understood what was going on when he talked about how there wasn't anything in the world that could stop a scared little boy who wanted his mommy. It's been a long time since I explicated on it, but I seem to remember there being some other stuff from the new series that supported my supposition that a lot of the Doctor's issues come from the fact that he had a human mother who died when he was very young. And it was even more shattering for him because, on Gallifrey, no one dies. They just regenerate. He (and his father) would probably be the only people on a planet of immortals who'd had to deal with that kind of loss, and knowing the Time-Lords, the rest of them probably weren't very empathetic towards his situation. And that's why he runs.
Years later, after "Journey's End," I figured that the perfect woman would be one Donna Nobel. Getting into a pre-Time War period the only way anyone can, by living into it, she eventually meets a dashing man unlike any other who sweeps her off her feet and then takes her to his distant home planet to build a family with her. And one day, something about her young son reminds her of the man he was going to become and, bang, "Where's my mummy?" And
that's why he never dares to look back at what he's done. Kids often assume that anything that goes wrong in the family is somehow their fault, and even if he didn't understand how it was possible, the little Doctor would believe he'd somehow made mommy go away.
(The actual thing that made me think it could be Donna was that it just seemed so damn arbitrary that it was her who combined with the spare hand, but it was so predestined and built up. I mean, there were a dozen things that meant that Rose and only Rose could make the Bad Wolf that were unrelated to it's predestination, but the only reason we got the Doctor-Donna and not the Doctor-Jack or the Doctor-Rose was that Donna heard a noise and didn't step out of the TARDIS as quickly as the others, making it a self-fulfilling prophecy. The plot-hole would be filled handily, however, if Donna was the only one who could make the metacrisis work... say, because she was a relative of the Doctor, and Jack and Rose weren't.)
It also has a funny little thematic tie with everyone assuming the Doctor and Donna were a couple; they were actually related (though she seemed more like a big sister than a mom, which could go back to "The Empty Child" again).
Of course, now that's all kaput, since the Doctor left an auto-wipe in Donna's head so she'll never actually
die of Time-Lord-itis, complete with energy-bomb-thingy to give a right smack to whoever reminded her of something Time-Lordy, and she's gotten married to a guy with absolutely no resemblance to William Hartnell (though I suppose he
could regenerate before they go back to Gallifrey...)
