Just remember that the gains you made as a teen were not all because of weight training but because of growing into adulthood which would have happened if you never trained. The only way a person can actually know specifically how much they gained from weight training would be to start weight training for the first time as a full grown adult while measuring bodyfat levels along the way. My guess is most people who train naturally only gain 10 to 20 pounds of muscle total from weight training.
I'm a damn midget bro.

I started "growing into adulthood" at 12-13, and it stopped at 15. Hence, me taking up weight training. If I wasn't going to grow taller, I figured I might as well grow wider.
I get your true point, btw.
I disagree on the 10-20lb figure though. I was a skinny-chubby 125 b4 I started at 16...i'd guess 20-22% bf . Adulthood bone and naturally occurring muscle density growth likely added 30lbs (I feel I'm being generous with that) which would put me at 155 if I never lifted. I'm stocky-chubby currently....19% bf with calipers, and weigh 192-194 each morning. So that's close to a 40lb difference, 20-30 more than your suggested range.
Before you come back at me with "You've said you've been on trt for about 15 yrs", I'll just tell ya while keeping personal stuff personal,... That's true, but it's been on and off (it does get old, and there's a lot of other things in play with my health that has 0 to do with bbing or AAS, as well as a serious accident.....two 3 yr stretches of doing no workouts) That's why I said I agreed with you about the shrink-grow cycle thing you talked about. It definitely applies to me although not by choice as often as I'd have picked. Also, out of that 15 years, I had one 1 yr segment where I trained hard and ate right consistently, and then another 10 month stretch where I did so as well. I started back in the gym only 2 months ago, and TRT 3 months ago and weighed 199-204 in the mornings. So trt does not make the changes people might think it does. I'm just less depressed, angry/aggravated, and tired.