The litter-ature over the years has teachings that imply Jehovah's Special People are all on the verge of having unplanned sex on a moment's notice, with anyone, at any time.
You must have a chaperone if you are to be alone with someone of the opposite sex, even briefly.
This applies to people of any ages. You could be a 99-year-old raisin whose flagpole hasn't risen since Rutherford was living in Beth Sarim, but you still shouldn't be alone with a pimply 16-year-old shy obese virgin who still plays with Barbie Dolls. She's a seductress! You may get inflamed with passion TM and suddenly have sex! (I mean who but sex addicts would have sex under all the conditions that require a chaperone?)
Even sitting next to each other at the kh can cause you to become an unwed teen mother!
It is high time for girls to understand the make-up of their bodies and its functions, especially with regard to sex. Then if a girl understandingly takes care of herself while the ovum is at large and is causing sex disturbance and cravings within her, she will be able to act like a true lady of irreproachable morals at all times. She will avoid the violating of her virginity and the shame and conscience-stricken state due to this; and wisely she will direct her young life so as to end up in the position of a clean, happy wife and mother of legitimate children, journeying to the new world of righteousness, where there will be no sex problems amid a sex-crazy population.-- Watchtower 1961 December 15 pp. 767-768