My son's school has recess up to grade 7, but I think grade 5 would be a better guess for learning the meaning of the word lesbian and also the quality of the handwriting. This is also about the time I recall girls and boys starting to have crushes.
I mean, I'm a gay guy, and is pretty much agree. "Pretty" is a pretty loaded term that almost by its nature implies femininity. Linguistics are weird, and while many things can be pretty, pretty and attractive aren't exact synonyms. I find men way more attractive, but there are far more women I would apply the term pretty to than are there men I would I would do the same.
Though, I wouldn't compare women to an old shoe, and frankly I'm offended by the little lesbian for besmirching my gender. We are not like old shoes!
It takes some kids longer to figure things out than others, but if they're old enough to feel attraction to people then they have developed some amount of their sexuality.