Do you think it's possible to tell if a child is gay/trans at a young age?

My little bro is three years old, and he is distributing some interesting behaviors to say the least! He tends to like typically "feminine" things. For example, we have a very girly cousin. My brother asked to wear makeup and paint his nails. He likes the shows Doc McStuffins and Sofia the First better than other kid's shows, and asked for a purple dress like Sofia's. He loves putting on chapstick and calls it lipstick. He likes growing his hair out really far, and depending on the day, his favorite color is pink.