At least the moon landings lot have a plausible reason for their theory; the US did genuinely want to win the space race.
Lots of families, especially posh ones, have grubby secrets they want to hide, usually involving babies born out of wedlock, babies born to affairs, people marrying "beneath them", useless Wrong Un eldest sons, failed businesses, alcoholism etc. I just genuinely can't think why anyone would initiate a convoluted sex change swap. If you wanted France run in a particular way in the future, wouldn't it be easier to just run for President yourself?