What causes some people to be left-handed, and why are fewer people left-handed than right-handed?

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I write with my left hand but play sports like tennis with my right hand. I cant do either of these well vice versa so do I count as ambidextrous or not?

I noticed I use my left hand for stuff often but consider myself right-handed. Is there a thing where you're semi-ambidextrous? - Quora

Why do left handers write so awkwardly with the hand curled over

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I am right handed. Recently, someone noted that I write like I am

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Why do right-handed scissors not work when a left-handed person uses them? - Quora

What percentage of the world's population is left-handed? Is there a difference between the percentage of left-handed people in different countries and cultures? Why might this be so? - Quora

What is happening to my brain if I suddenly using my left hand to eat rather than the right which I was always used to using? - Quora