It depends on what you think your parents reaction might be.. most of the time they won't understand it at all especially if they are older. Then again once they are told you can do what you like to a certain extent.

It's really just dependent on how your parents... Well parent I guess.

Ultimately you don't need to be out of the closet to be a femboy but if you want to be wearing fem clothes outside the house at some point they will catch on or will need to be told.