[anon291]

If you have no distinguishing organs that produce sexual cell lines via meiosis, and have never ever had such organs, then you are functionally sexless. This seems like a reasonable position to take. Given our understanding of embryology and development we may try to piece together what would have happened had something not gone awry and base our judgement on that. But if we don't know, then it's hardly unreasonable to simply say 'I don't know'. However, we are not being asked to acknowledge that we cannot know for some individuals, we are being asked to accept those with obvious organs and gametes of one sex as individuals of the other.