Quote Originally Posted by Zyzzyva View Post
"X runs in the family" is a fairly common English phrase: "good looks run in the family", "madness runs in the family", etc. So we have a book with X replaced by "blood": the implication is that "blood" is a quality that all of the family** possesses, and is unusual enough to be notable. But of course every family has blood in it, it's even how we refer to family metaphorically ("blood is thicker than water", etc), so saying that "blood runs in the family" is redundant and bathetic. It's basically the same source of humour as The Long Dark Tea-Time of the Soul. It's not a pun, no, but it's clearly not the title of a serious book either.
Zyzzyva is right.

Blood Runs in the Family is intended to be, if not laugh-out-loud funny, at least a bit of wordplay. "[Trait] runs in the family" and "[trait] runs in the blood" are both two expressions that mean the same thing. "Blood runs in the family," therefore, combines the two phrases in a redundant way, like saying, "That pie was as easy as cake," or, "The drawing board got sent back to Square One," or "That cup of tea is really my bag," or "That dim bulb is really not the sharpest tool in the shed." (All of which are terrible examples that I just pulled out of my head.)

That it also fits, thematically, with the content of the story is why I picked it (including all the interpretations that allenw listed above), but I'm baffled that anyone could look at it and think it was an entirely serious choice. It's an absurd title. I might as well have called it, "The Dark and Stormy Night of the Dark Storm at Night."

EDIT: A better in-comic example that just occurred to me: Crystal yelling to Haley that she will "kill [her] to death!"