People can often be insecure about themselves, without realizing it. Also, they tend to have a fear of anything they don't understand.
Now that is a recipe for some unpredictable reactions, reactions that they themselves might not expect from themselves or know to control. And the other thing is, that a lot of what people perceive, is read subconsciously. They don't know why they feel a certain way. Read up on "Uncanny valley" effect, there's even an article on it in Wikipedia... When you read this and you read that, taking it together, you will probably have a better understanding of transphobia than half the psychologists, and see it for what it is, as a manifestation of weakness more than anything else. A reaction of their "inner animal" to something that they can not comprehend. Their mind, trying to divide by zero.
I don't claim to know everything, all the answers. I don't. I know some. I hope the encyclopedic nature of my mind doesn't come across as pushing, intruding into your world, making you insecure. I just want to help, and do that thru logic and understanding.
-Xx
