" I could have been a high school sports star !"
Having 2 son's myself and having grown up as a JW I understand how you and your Son feel;
I was asked to be on the High School swim team (my non JW Dad was well known for his swimming in his home town) however my JW Mom wouldn't hear of it. According to her all knowing Watchtower magazine, I might get into drugs or immorality if I was on the swimming team.
Much to the criticism of the congregation and eye rolling on the part of JW relatives, We allowed our boys to be on the wrestling team, Lacrosse team and one of them was a swimmer. They were both easy boys to raise and other than being very untidy, they were a parents dream.
Being on these teams helped them immensely in terms of being more outgoing, facing difficult tasks and sticking with things and they just had a lot of fun. We also let them go to the prom and one of them was the Homecoming King. The elders knew better than to say a word to me about any of this. One of my Son's is still attending the meetings (barely) but on his own has picked up on TTATT and the other one stuck with it until about 22 and then a few things happened in the Hall made him hang it up when we did.
Having said all that, they at one time or another when they were going through a difficult time or in a low mood or feeling that they weren't were they wanted to be in life, indicated that because of our religion, they sort of missed out on a normal childhood in terms of not getting to date and go to parties or stay at other non JW kids houses or go places with them. I found myself feeling a bit guilty or wondering if I could have done more for them. Then I realize that if we want to talk about could have beens , they also could have been in a car accident while out with friends, or had a pregnant girlfriend, or gotten hooked on drugs or any number of negative things, if we'd have given them any more freedom than we did.
I warn them in so many words, not to go down that road with me and remind them that there are lots of other weird religions out there that they could have grown up in and negligent unfit parents out there who's kids have a right to complain about their childhoods, but you two had the best of both worlds. Yes we went to all the meetings and out in service and didn't celebrate holidays etc but we tried to give you a balanced upbringing unlike the ones we had as strict JW's. Your Mom and I didn't just provide you with the minimum the law expects, we went above and beyond, giving you tropical vacations, took you snowboarding regularly, braces on your teeth, a clean home and delicious meals, bicycles, a car and mostly our undivided attention and love. That sort of brought them to their senses and got them off the pity wagon and back on the road to taking charge of their lives.
Your Son may just be feeling badly about his own limitations right now or what he views as personal failings and may be looking for someone other than himself to blame it on. It's good to let him get it out of his system but totally buying into the idea that your being a JW was the single factor in him not being a "star" is allowing him to use blame as an obstacle to moving forward. Remind him that you are the parent and what he thinks of your choices of religion is all very interesting but the bottom line is, as a parent it was your choice to make. Yes, maybe he could have been a "sports star" but he could also have ruined his knees or been in a debilitating sports accident. I wouldn't buy into the idea that this is your fault, rather I'd ask him how his life would be really be that much better or different even if he was a "star". Was it missing the fun of playing sports that he regrets or is it that he wanted the adulation of others. If so, why? I'm assuming that no one stopped him from being on the debate team or from being on the honor roll....who does he blame for not being part of that ? (I'm assuming he wasn't) Rather than allowing him to dwell on what could have been, I'd direct the conversation to formulating a Plan B. He's only 17 after all.