That's interesting. Baba Yaga, traveling through time by uploading her mind into host after host, decides to make a more compatible host, and produces a child to be her next host.

My position for a while is that Quirrell is grooming Harry to be his next host, and who better for the Dark Lord to move into, than the Boy Savior as he defeats the Dark Lord?

Though as Quirrell, presumably "he" could have fathered Harry through Lily. However, it kind of fits the story of that Munroe guy that Harry is actually a replacement baby left behind when the Potter family was exterminated. That would be the 2nd Old House that was killed off and left with a single replacement survivor.

But the thing is, if uploading is an integral part of the story, he's already committed to that complication, and so it adds little further complexity to say that he uploaded some chunk of himself to Harry, and a biological explanation becomes superfluous.