I think I agree with you that they shouldn't go there. It'd be like discovering Dad's a bigamist and has a whole 'nother family in another city.

I happened to be thinking just this morning about our profound attachment to the Doctor down through the years. Seems to me that a significant part of it is the thought that our lonely species has a friend and protector, somebody who, through the magic of time travel, will literally always be there. It's significant that the Doctor is non-human, so that he can validate us, that there's at least one person out there who loves us in spite of our many flaws and thinks we're worth saving.

Yeah, episodes like "Listen" are moving when they reveal something of the Doctor's early life. But they also feel somehow dangerous, like we might learn something we didn't want to know, or that we're intruding where we shouldn't. It complicates our relationship with the Doctor to think he had a life before us and might to this day have other loyalties, loyalties that might at some point come into conflict with the Doctor's professed love for us.

Disquieting.