I think the first two stanzas work well, actually - one of the things that my husband likes to ask me after I write something is, "Why?" Did I write something just to write something, or do I have a specific story to tell and reason to write this? In this case, while the "meat" of the poem is about your mother, if it wasn't for those first two stanzas, I'd find myself wondering, "Why? What is the reason she is sharing this with us?"

I agree that the first two stanzas seem incongruous, but rather than cutting them, I'd suggest expanding on the poem a little more and bringing it back around to the beginning at the end. It's clear that the intention is, "Did she just say my son looked gay? Well so freaking what?" and I love that you go back to your mother and back further to her uncle and what they had to deal with in a time before that was acceptable, but now you can bring it back around to your son and talk about how you hope for him that, no matter what he becomes in life, he's living in a time where he is free to be who and what he chooses, like illustrating, 'Hey, there is some hope for the future!'