In wildlife park 2 how do you get peculiarities of nature

Certain animals will produce peculiarities of nature when bred, if both parents have the required genetics. It is hard to find out which animals of the ones you first buy would have this required genetic, so I personally start off wihh a male and two female, and if neither female produces peculiarities of nature, I get another male. If there is still none, I get two new females to test with the males. If there is a peculiarity born, I breed it with it's sibling or parent to continue getting these special animals. As far as I know at the moment, only the saurians, crocs and tigers produce them, so if any one else knows of others, please inform me. (I started my own question called "Which Animals produce peculiarities of nature in Wildlife park 2?")