Are they really lesbians? People both like and dislike the show because the gems are supposedly gay, but people also say they don't have gender. Which is it?

Also, some quotes from a Q & A with the creator:

Q: Is there any particular reason the Gems use feminine pronouns if gender is irrelevant to them? I would understand if it were just more convenient.
A: There's a 50 50 chance to use some pronoun on Earth, so why not feminine ones-- it's as convenient as it is arbitrary!

Q: Will we ever get an explanation in the show why Gems have the form of human females? If not, could you explain why?
A: Why not look like human females? That's just what Gems happen to look like!

Pastebin source: http://pastebin.com/TJadRsiB