I also hold my child with my left hand as I am right-handed. Obviously, it allows me to do more since my dominant hand is free for more complex tasks, as stated in the article.

I only thought about this recently because I had a 'test' on my body that determined my left arm had more muscle than my right arm, and the person administering the test asked if I am left-handed as a result of this. I couldn't figure out why this would happen, thought about it for a day and realized the common repetitive motion I do that might strengthen my left arm significantly is holding a 20+ lb child.