Want me to elaborate? Children are fickle in many things. Exploring the difference between girls and boys is very normal, and during that process they wonder what it's like to be the other. This is an innocent idea, and parents that encourage what your talking about are encouraging them to think too hard about it. Push the thought process too hard and thoughts become reality. Parents should do their best to solidify their kids identity as they were born. If you're a boy you're a boy, and if you're a girl, you're a girl, and live that way till adulthood. And later on, if they want to make that decision (although I disagree with it wholeheartedly) it should be an adult decision on their part that they make for themselves, with a real understanding of what the consequences are. A child cannot understand the concept of time, how long does it take to get to Disney Land, much less what it means to make changes that last a lifetime.
That enough words? Cant let peewee best me ;)