This brings the problem of the size gene affecting the ratings of the animals. This results in punishment for players wanting to use smaller creatures. Instead of variety in sizes, you end up pushed for the genetically biggest zoo animals.I suggested this on the other thread already, but the best solution in my eyes would be to make the size range between 0-100% more extreme. 0-30% representing the miniature variety being the size it is currently and 70-100% representing the big one.
This way you technically have all the variations