Board Thread:General Discussion/@comment-98.218.70.24-20150317164438/@comment-3257939-20151021021134

I thought about this too. She doesn't necessarily needs to know. Ruby and Yang look nothing alike but Yang herself looks almost nothing like Raven or, at least, that's what you'll think if you didn't see her face. So basically, there is no reason why Ruby would bring this up. Yang looks like her father and has his surname while Ruby has the same from Summer.

Basically, unless Taiyang and Yang talked to her about this then Ruby wouldn't figure it out herself.