[quote=DamageOverTime]
Yea considering that one is bright blond with an Asian name (but looks Caucasian) and the other is a black/reddish head (also looks Caucasian). I think they did mention in the start of season 1 about a father but I cant remember exactly I'ma watch it again.
[/quote]

They comment about their father a few times: I think it's episode 3 when they're at the sleepover and Ruby comments "Dad wouldn't approve of all the boys" and Yang responds with "I know I sure do."

Then an episode or two after that, Yang is telling Ruby to get out of her shell and Ruby responds, "grrr, you sound like Dad!" 

They don't really talk about their mother, though, which is why I think it's the father they have in common. The only time Ruby speaks of parents together is when she's explaining to Ozpin why she wants to be a huntress: "Our parents always told to help people so, y'know, might as well make a career out of it."