[Watanuki hadn't even considered the possibility that Merlin might just not be familiar with Eastern magic. But if that's the case, then why did Yuuko send him here? Why not train him herself, or at least send him to an Easter mage?

Though a moment later, Watanuki realizes he's looking at the problem backwards: instead of focusing on the fact that Merlin isn't an expert in a kind of magic that Watanuki might be more familiar in, he should be thinking of why Watanuki was sent to study this kind of magic. Hmm...

For a moment, Merlin will feel that tug of Yuuko's wish magic again. It's the same as the time Watanuki stumbled over the magical blocks on his memories, though not quite as strong because Watanuki is more carefully toeing around them this time.]

I think...my father might have had some Western ancestors. Very far back, perhaps.

[He sounds unsure of it though and he's starting to get a headache, so he's going to stop trying to think about his family directly.]

Could that be why? That somehow I've inherited some magical capability from an ancestor, a power that hasn't shown up in a long while?

[That would certainly explain a lot. As far as Watanuki knows, his parents were not mages.]