[atlaw]

"I'm under the impression that for something to "evolve" the baby had to be different than the mother."

In rudimentary terms, you are correct. But the mutational "differences" are small and are not necessarily morphologically apparent within one or even many generations. For a very rough analogy (and one that by virtue of human intervention is itself foreshortened), think of the time and the number of generations it takes for humans to selectively breed plants and animals.

[atlaw]

And Vade provides (as usual) a perfect example. Although I expect that you will object because, despite the differences from one generation to the next, humans are still humans and double-tailed goldfish are still goldfish. But ... one step at a time.