My reading (extensive) turned up that what was once 10% of the population is moving closer to 15%. Also be aware (for your child) that left handed is often right brain dominant, more imaginative, image oriented, creative, than strait line analytical. Been there done that, being lefty, four out of the six kids lefty, and quite a bit of ambi among all. Tefillin is just opposite/normal, lulav is a machlokes, and kiddush preferably with the right hand. My take is that most children terrorized by scissors that don’t work, will accommodate to some right hand use as they grow, and some will eventually put on tefillin on both hands (not at the same time)
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