I'm glad it's a girl, because that's FUNNIER

If the internet scuttlebutt is true, David Tennant and Georgia Moffett have a daughter. (It's confirmed that they were sighted in the antenatal department of a London hospital two days ago--the birth is as yet unverified.)

So, the joke is complete, as it is the Doctor's daughter. And his granddaughter. Also, the Other Doctor's granddaughter. ALSO also the Other Doctor's daughter, since the Other Doctor is the same Doctor as the Doctor who just had a daughter. Also the Doctor's daughter's younger sister, and therefore the Doctor's Other Daughter (and, thus, the Other Doctor's Other Daughter). Thus, finally, the Doctors' daughters.

And, you know, let's not forget, the Doctor's Daughter's daughter.

I suggest they name her Timey Wimey Tennant Moffett.