One of my earliest gender alternative moments that I can remember came from kindergarten.
I remember the way our kindergarten room was set up, desks towards the front of the room, the back of the room having a thick carpet to play on, low shelves full of toys, games and blocks, and in the corner, a "house" type setup complete with fully stocked kitchen, table, chairs, high chair with baby, etc.
My favorite toy was the bristle blocks. I could play with those all day, every day, and I tried to. I was always the first to get to them - I bypassed the wooden blocks, legos, games... just so I could build with those blocks. I loved building things. Wooden blocks came in a close second, if the bristle blocks weren't available.
At some point, the teacher decided I shouldn't play with them anymore.
I remember I went to get the box of blocks from the shelf, and she led me away from them, taking me over instead to the kitchen where the other girls were playing. They were cooking, taking care of the baby, having tea at the table, and being.. well.. girly. I think I might've wrinkled my nose.
I didn't want to play house. I didn't want to be the mommy. I wanted to build.
The teacher wouldn't let me go back to the blocks, she insisted I play in the kitchen. The other girls tried to get me involved, I guess, but I wasn't interested.
I finally broke down and told them I'd play, but only if I could be the Daddy.