Why can girls crossdress but boys can't?

Anyone can crossdress. However, when a girl does it, it is usually out of common sense, that they are doing something to which pants and shirt are more appropriate than a skirt or heels. Why would a boy want to crossdress? What might be a practical reason be that a boy might be better served in a skirt and heels?
  • Throughout centuries girls have been brought up to be dainty, but during the 1940s and up women began to wear slacks (like a man) and sometimes even neck ties. In the 30's Marlene Deitrich was the first woman to boldly wear men's slacks; a neck tie and sometimes a top hat and had been seen in a man's full suit. However, because she was a celebrity she got away with it. Some girls were classified as tom boys (such as the actress Debbie Reynolds) who always seemed to have roles as a tom boy, but, in fact, is quite the dainty little woman. Girls were and sometimes still are reprimanded by their parents for not acting like a young lady should. From the time a male child can first understand they are taught to be strong; not cry; play with trucks; get into sports because it's a structured male role play. Some male children are simply not interested in any of those things and may prefer to read or get into other interest that are less aggressive. They are also brought up not to dress in young girl's clothes or older women's clothes and society has mistaken cross dressing for being gay when this is not often the case. Men simply shouldn't do this according to society and should put one step forward as being strong and 100% male as they are there to protect their country to their wives and family. Women, considered the weaker sex basically get away with more things than the stringent male role model.