To non geeks it is just another birth announcement. Actor David Tennant and his girlfriend Georgia Moffett (daughter of actor Peter Davison) are parents of their first child together.
However if you are a Doctor Who Geek you could put it this way…
The Daughter of the 5th Doctor who played the Daughter of the 10th doctor started dating the 10th doctor and has given birth to her first child, who is also the child of the Tenth Doctor.
That makes this kid, the Grandchild of the 5th doctor, the child of the 10th doctor the son of the daughter of the 10th doctor who played the daughter of the 10th doctor making kid the grandchild of the 10th doctor as well as the child of the 10th doctor who is of course the same person as the 5th doctor. And of course since the Doctor kid’s mother is the doctor’s daughter that makes the kid the sister of the doctor’s daughter since he is the doctor’s kid who is also his mother. And of course since she the 5th doctors daughter went to school with the 6th doctor’s daughter we could make it sound even more complicated than this if we wanted to.
Yeah I know it doesn’t mean anything but all I could think of when I heard about it was that old song, I’m my own Grandpa.