I've suspected this in the past, mostly because I've noticed that my horses are usually better clock wise if they are horses I've trained from the ground up, but it appears my imbalance is at fault for our canter/turning issues to the left (counter clock wise). I had someone else ride Primo, that I have coached and know that she is severely left handed, interesting that she had less issues and achieved a much nicer canter through the turns.
I had a horse land on me way back when and have not been right since. I just recently started ballet up again and wow do I lack strength in my left leg. My dance instructor recommended spending more time on that side and lifting. Does anyone have any other ideas for restrengthening the leg? Anything I can do while riding? I'm a bit miffed that neither of my riding instructors have ever mentioned it.