BDS4.4 has already died. Its first child 386BSD has died too.
Of the three children of the next generation, it can probably also be said that NetBSD is really not in good shape. OpenBSD is still fighting (that's the warrior of the family... he tries hard to die on the battlefield). Did not have much news from FreeBSD recently (it was at google last time I checked). I hope he's well.
DragonflyBSD is the newest generation IMHO, with lot of brilliant new ideas; but still has to prove itself in the field. (Again, did not check for a couple of years.)
On the darwinist path, Linux is the one which is still single without legitimate children... ;-)