I was in your son's shoes long ago. I had been visiting with an Army recruiter as I had zero interest in serving a mission. After I turned 18 I decided to join and left one morning early with the recruiter and signed up. Problem was I had to wait several months to actually leave for Basic Training. The wait was interminable and frankly I wish I had left right then, but I was still in my senior year of high school. I joined on a saturday and went to church on sunday facing a barrage of various ward members making their opinion known of the horrible choice I had made. Bishop, Priest Quorum leader, et al were all involved in a concentrated effort to talk me out of my mistake. Anyway- this went on for several months and by the time I had left I was very angry and I pretty much bailed on the church because of the non-stop badgering. Granted, I was not up to speed morally to even go as I partied pretty hard and smoked some...of course back then all you had to do was confess and all that and you were in. I spent a long time on active duty angry at how I was treated and attended church three times in my first four years. Twice in basic training and once at FT Bragg. Eventually I settled down, married in temple, got my degree, had kids and all that happy stuff. Fast fwd to the present. From time to time I see a kid who doesnt want to go and see them get some pressure- it makes me physically ill as I relive my experience of being harassed. Not good as this means I have probably not let it go yet and frankly I dont think I ever will. So- tell them to leave your kid alone. A mission is a good thing for those who want to serve, but if one is cornered into it probably not the best idea. Besides, there are plenty of guys out there who didnt serve a mission who turned out pretty good.