Add [blank] for gender and set it to default.

You can put whatever you want in that 'enter your choice' box, but if you don't put anything in it then it will use whatever option you have selected in the dropbox above it...if you just want it blank, why not just put a dash or a dot in the box?

 

You can set a blank gender by adding a blank space into the gender box (like I do), but that's definitely not intuitive, so it would be good if this were changed.