Jo Maugham retweeted a response to the 'human bodies have limits' line which says that we should rip out grandad's pacemaker, because we must never use medical technology.
You know, we use pacemakers precisely because there are limits to our medicine. We can't make people grow a new heart or give them a magic pill to make it better, so we have to resort to an artificial cludge like that.
And if we can't repair someone's heart, how on earth do people think we can make people change sex?
(I figured this out when I was about 12 or 13 and read about a "sex change" and could tell that that did not tally with known medical technology).