For the human side of the coin, I think it is very helpful for people to understand biologically why transexualism could occur. I mean, it could be a chromosomal abnormality during the fusion of gametes, or perhaps something resultant from abnormal chemical signals during development. At least in my opinion, it makes the entire matter more understandable and less mysterious- which is why I love science. To me a good person (or fish!) is a good person no matter what. That's not to say that I wouldn't have some response to learning that a loved one was transexual...but I would support them no matter what they chose in life.
Getting back to the original thread...the little girl in my avatar was definitely a female and her fins grew longer than they are in the pic. You just got extra finnage on your girl :)