Can boys play dress up?

I am an education major and I am doing my practicum in a daycare full of sixteen four- to five-year olds. A couple of days into it, I began to understand the differences in interaction, language, and activities between boys and girls. The girls like to play mommy and baby and the boys play “good guys bad guys” during dramatic play. I remember from this class looking at the different toys, clothes, and books, which are placed into categories for boys or girls. However, should there be this distinction of what boys can play with or what girls can play with when they are younger.
Two weeks later, I was observing a boy dressing up boys clothes and enjoying it. However, the teacher told me that he used to dress up in girls clothes. I did not and still don’t, think there is anything wrong with boys dressing up in girl’s clothes. Apparently, the change from dresses to hats and suit jackets was from the influence of his father. His father did not like the fact that he was dressing up in girl’s clothes because maybe he thought he would turn out to be gay. I think that young boys and girls should experiment and explore different activities, clothes, games, because they do not know the difference. Children should not be forced into the gender norms or society by their parents or guardians, children should be able to choose where they fit in with society or in this case, their classmates.