Board Thread:General Discussion/@comment-25375901-20140918010005/@comment-3257939-20141001044406

Exactly. It simply doesn't add up. It's more like a crack theory so it should be in the Speculation House... or tumblr.

The only thing that is similar between the two of them, the only thing that may turn this crack theory into and actual headcanon is the fact that Cinder is chinese (according to Monty but that could be just a joke) and so it's Yang's father judging by his last name. If anything, the only person who is likely to had Cinder with another person is Yang's father, not her mother.