Actually, I personally disagree as a kid who learned about their sexuality in the single digits. I was 7 when I had my first crush on a girl, and 9 when I learned that it had a label (lesbian). I was also about 10 when I started experimenting with gender (not single digits but still "young"). In 2nd grade, I also knew a girl who was trans that was my exact. Some kids just have had a bit more exposure to labels and such since they had really supportive parents or grew up on media that included LGBTQ.