I find your Down syndrome reference highly insulting, and even more unintelligent and ignorant than the insults directed to CDs and TGs you are referring to.
TGs and CDs are maybe harder to understand. Not even us can understand it completely, and many people react based on their deep ignorance about the subject. The media doesn't help either since there is not a single positive portrait of CDs or TGs, other than mediocre comedies.
But knowing a little about Down syndrome is just about having just a very little amount of education and common sense.