Replication error on DNA during Asia‘s propagation.
In the propagation of Asia, DNA will be crossed or copied. Normally, crossed 2 DNA will be replicated to another new DNA but sometimes errors likely to occur. Those part of the replication errors possibly change the reproduced Asia on its shape or character. In some case when mutation occur, that affects its shape or color directly so that you can distinguish obviously. Or in the other case when mutation that affects its characteristic, it would likely to occur that a child has quite different character from parents, for example, two vegetarians might create meateater accidentally.
However in the another case, the impact may be very little since the difference caused by this replication errors may be very little part of whole DNA.
