I grew up around hunting and shooting but I had to teach myself how to hunt due to some family dynamics, except for duck hunting with my older brother. I learned how to bow hunt at 17 (I did have a friend that helped me learn), rifle hunt at about the same age (transportation was an issue). As I got older, I hunted at every opportunity, talked with older hunters (and listened), and by the time I was about 30 I considered myself a pretty good hunter. If I had had an older mentor, I probably would have been a much better hunter overall, and a good hunter much earlier on.
I would say that if we want to keep the sport alive, we need to take someone hunting, introduce others to shooting and hunting, talk about your hobbies with others, and in general don't try to keep it a secret. Offer your knowledge and experience as the reward for the other person learning to be a good sportsman, be forgiving and considerate of your companion's mistakes and ignorance, and don't be afraid to withdraw your support and friendship if the other person turns out to be a jerk. If we do this, we will win friendship and companionship for our hobby.