This question probably deserves a more complete response. Sit back I'm about to blow your mind.
To the question: does this happen like in the story? Short answer no. Sometimes in some animals yes, not known if it could happen in humans because of some population triggering epigenetic change like in the book, but best guess right now is: oh hell no. The animals that have been observed to do this are so distantly related to us it is unlikely to be a thing humans can do naturally. Now if apes, or monkeys or other mammals like dogs and cows had been observed to do this it would seem much more plausible. But if you've ever been to a dairy farm? Alot of cow not alot of bull, no changes have been observed.
That being said...... it does/can happen in humans atleast the other way round (Female to Male), depending on how you mean it. And not for balance of population reasons.
Here is some mundane trivia:
All humans started out life female by form, as the pregnancy progresses however 'typically' those with a Y chromosome develop penis and testies. This is one of the reasons ultra sounds alone can't detect if the fetus is female, Presence of a peen means Male for sure, but absense means.... lets just wait longer. Eventually either the penis forms, or it is so far into the pregnancy one can safely assume female, in a world with ultra-sound and no easy genetic testing, say the last century it was not uncommon for healthy baby boys to be brought home to a pink and frilly nursery by throughly confused parents. The other way mistake is not so easy to make as this change is strictly one way F -> M. Also genetic testing is also sometimes a miss, plenty of females exist with Y chromosomes and some have been known to produce children.
And now for the fun bit....
Very very rarely humans have been observed to make this female to male switch at puberty. Basically some boy is born with boy genes and girl parts, back before genetic testing a child with no boy parts must clearly be a girl. So these children are raised as though they are girls until one day, usually at puberty, their parts change, they become a boy. (and I bet you thought your body changes at puberty were rough). The TV show "House, M.D." did an episode with this or a similar condition in Season 2 Episode 13 "Skin Deep". Basically a female teenage supermodel is brought in with symptoms, House does his usual hypothesizing and testing. Eventually the diagnoses is: Testicular Cancer! because of course it is. It is never easy (or Lupis). Interesting to note that the girl's balls should have dropped because she was in puberty, so the writers gave her "Complete androgen insensitivity syndrome" which would explain both the reasons for her lack of change and the supermodel career.
Short answer: A natural shift of sex from female to male can be observed in all human males usually in utero, but in rare cases as late as puberty. |