We are talking doing some bird hunting.
We have an interesting cross section of opinions. Certainly no consensus.
In the context of what I opined above (and my right eye dominant and left hand situation), I grew up in NW Iowa in the sixties, a time of plentiful Government Acres (now the diminishing CRP acres). Pheasants were bountiful and in the those "Mayberry RFD days," long before I had a driver's license, I would carry my dad's old H&R 12 ga through town to the railroad tracks on the south end. It was there I killed my first pheasant at twelve or thirteen or something.
As a frosh in college, a friend who had GSPs and I, legally killed very close to two hundred birds in the fall, using every snowfall as an excuse to go and do "field research." In fact it was. My biology term paper consisted of the results of examining the stomach contents of about a hundred birds.
Perhaps my right eye dominance isn't as dominant as one can be over the other as intimated above by others, but as soon as I realized what the correct sight-picture for a solid hit looked like, I never struggled again (that's certainly not to say I never missed again). This was with inexpensive shotguns and even as I graduated to better and more expensive ones with cast-off stocks (better for a right hander) that I was ignorant of, I never had a gun that I couldn't regularly hit with.
I now shoot mainly SxSs with cast neutral stocks. I'm not meaning to negate the finer points of cast, eye dominance, and so on in the formative instructive years in leading to reaching one's potential in wing shooting. I am a fine field, wing shot but would probably be beaten in formal sporting Clays competition by the best and maybe badly. As in many endeavors, there is very little difference between very good and excellent but the difference is in paying attention to those details.
Perhaps, see what your son does spontaneously when handling different shotguns and firing at some clay pigeons, not only in the air but stationary on the ground. I wouldn't force him into something that feels totally unnatural to him but there are some real disadvantages to "going lefty" in the gun world too.
