“Wikipedia has an ‘age of consent’ page. Lots of places have a minimum age of 16 and some of those even have a 4-year close-in-age-exception. What that means is if a boy is 18 years of age or younger, he can have consensual sex with a girl as young as 14.
There are a large number of foreign countries with an age of consent as low as 12. But that might apply to one of the “close-in-age” exceptions. Nigeria is 11 and the Phillipines and Angola are 12.”
Your authors suggest that you refrain from anything even remotely sexual with anyone not only under the age of consent, but also anyone who is not fully mentally mature.
The consequences of even a seemingly innocent, or ‘mild’ act can be surprisingly devastating to the young individuals, as their brains try to process the new information. It can include unbearable guilt, and strong feelings of low self-worth.
There are hundreds of thousands, maybe millions of adults in the world who cannot fully enjoy their own sexuality, due to long-lasting sub-conscious effects of things that happened to them in their youth.
If you find yourself attracted to a young person, go give yourself a great solo orgasm instead, so your hormones and desires will return to a better balance.