I wonder what it is like to have a gender change. Some changes in some animals occur naturally. 
Wow, You mean gender change in animals can occur naturally, what animals are those?
If I recall correctly some worms do that. But most what comes to most people's minds is surgery for humans. 
Yes that is what comes to my mind.  Do you know how common is gender change in humans?
No I don't know that. But I do know it is used in procedures for intersex people. 
It seem like a lot of risk and trouble to change gender so I guess they must really want it very bad.
Intersex people have various variations in their chromosomes and gonads and do not fit the definition of typical male or female. 
In that case I guess they are midway already if they want to change gender or choose one or the other.
Legal recognition of non-binary gender
Multiple countries legally recognize non-binary or third gender classifications. In some countries, such classifications may only be available to intersex people, born with sex characteristics that "do not fit the typical definitions for male or female bodies". In other countries, they may only (or also) be available to people with gender identities that differ from their sex assigned at birth.
Some non-western societies have long recognized transgender and/or non-binary people as a third gender,
in his image, then even if he fashioned us by some evolutionary means, he would presumably want us to resemble him in being able to know; but then most of what we believe might be true even if our minds have developed from those of the lower animals."
Plantinga defined:
- "N" as naturalism, which he defined as "the idea that there is no such person as God or anything like God; we might think of it as high-octane atheism or perhaps atheism-plus