When we go from 2 pairs of rabbits to 3 pairs of rabbits, we see a brother and sister rabbit mating to produce a pair of offsprings. This does not sound realistic and could also be disturbing to kids.

But for some reason, I have seen this example cited in many places. Why is this example so popular despite the implication of siblings mating while going from 2 to 3? Surely, we can come up with better illustrations if we try!