I got to see this during upfronts but since people have seen the pilot now and are talking about it, I'd like to clarify once again that
spoilers:end of spoilers
Barry was NOT adopted by Iris's dad, he 'took him in' which is totally different, and Iris, while clearly not viewing Barry romantically, also makes a point to say 'its not like we're brother and sister, so I get that its weird talking to me about girls you like' and there was a very pointed effort to convey that while extremely close, the two do not view each other as sharing a sibling bond.