// All mutation and no play makes queen a dull girl.
        float mutationModifier = housing.getMutationModifier(genome, mate, 1.0f);
        if(mutationModifier > 10) {
            if(housing.getWorld().rand.nextFloat()*100 < 0.4 * ((mutationModifier*mutationModifier) - 100))
                offspring.setIsNatural(false);
        }