Thanks, Helen for responding so quickly. I’d quite like to engage you in discussion over it, but it’s not easy in a limited character space. Suffice to say: I agree with you that it is best to start with the biology where we can talk about real objective characteristics. What goes on in our heads is really only known to ourselves. When it comes to biology, how many changes do you need to make before the assertion “sex is immutable” becomes untenable? I suspect that science isn’t finished yet.