Taking into account the wibbly-wobbly nature of time and the wibbly-wobbly nature of the Doctor Who canon, it's worth noting that according to the BBC webcomic "The Beast is Back in Town" the Beast wasn't actually destroyed by the black hole, but simply flung back in time to the 20th Century. On arrival, he takes control of the TARDIS with the laughably simple plan of ruling the universe.

At some point in his jaunts through space and time, it seems that he found the time to settle down and raise a family, meeting a nice lady-beast and siring a wee little beastling of his very own.