I'm going to try and say this delicately since it's a sensitive subject, and I don't want anyone to take this the wrong way.
Obviously, I don't think there is anything wrong with having gay characters in a TV Series. It's 2013. Willow/Tara all the way.
However, when the characters only exist to show up once an episode and say "Yep, we sure are gay!", I start to have a problem with them existing. It's been three episodes, and not much is happening with these two (the Daughter has stuff going on, and feels like an actual character with things happening to her, so whatever, she's fine).
Seriously, I know it's "only" been three episodes, but can you either start doing things with these two, or drop them from the show entirely? Because right now it feels to me like you only added these two characters (who I don't think are in the book?) so that you could show everyone how progressive your show is. Superfluous characters are bad, Under The Dome.