They say that if one throws a newborn into a pool, the newborn will instinctively start to dog-paddle swim.
Very young animals having fallen into deep water certainly have the instinct to dog-paddle, and is something their parents did not teach them.
You might presume that either-gender human beings can figure out how to have coital intercourse with the other gender by simply looking (either accidently or deliberately) at their own private parts and the private parts of the opposite sex. Specifically, they have - as small children - stuck their fingers into both animate and inanimate things, and pulled out those fingers again. They have seen gas-station gas pump nozzles inserted into open gas tank holes, and have seen wired electric-plug prongs stuck into and out of electrical wall sockets.
For a young boy, the mechanism of how his flabby penis could ever get rigid enough to stick into a girl's vagina is a mystery to him, and perhaps the girl wonders about that also. As the fellow grows older and passes puberty, his penis automatically becomes erect when both encountering photos, paintings, or live sights of substantially-undressed young women...and when physically contacting the opposite sex with (or being contacted with) various bodily extremities of his.
The Bible itself contains graphic-enough descriptions of what TO do sexually and what to NOT do sexually with the opposite sex. It is equally as important to know the details of what Scripture states we should NOT to for us to discover what exactly we could and should do erotically within the sanctity of marriage. It is then that the importance of marriage for legitimate and homorable expression of sensuous intimacy becomes evident to both teen and older men and women (not "minors" as contrasted with "majors"), so as to not defile themselves with licentuously-immodest and lasciviously-indecent impurity, sodomy, and fornication....
