I think girls are generally more pressured by society to be clumsier so, subconsciously, they tend to be just that.
But you could also throw in the fact that Aspergers is more common in guys such as myself, and since one of the best ways to be identified as an aspie is to have a reduced ability to not drop shit, I think an indirect argument can be made there too.
But I digress.
Clumsy about what?
Guys often are better in technology
Girls are more prudent and are often better in social contacts.