HOMEWORK: Can men wear women's clothing or can women wear men's clothing? Why or Why not

I think men can wear women's clothing and also women can wear men's
For example, I am a kind of small man. It's difficult to find my size. So I search my clothes in women section.
Also my wife is a tall woman. Whenever she buys shoes especially. She is looking for it = she looks for them in men section.
Therefore, men and women can buy their clothes in differenct gender's.