We did Vanilla x Fire in 2013. Some of the babies were obviously Fires, some were obviously Vanillas, and a few we had to wait to let them shed a few times to be able to tell for sure. So there isn't a really straightforward answer here....you might be able to tell and you might not. There isn't really a "way" to tell for sure, you just have to have some experience looking at them. I realize that isn't the most helpful answer, but that is my experience.