My folks weren't sure... I ended up writing right handed because of nuns... I mouse right-handed, because that's how they're made. If I need a quick password? That's left side of the keyboard. Cameras are right handed. I swing a bat or an axe left handed, but I can switch to right. I golfed left-handed until an employer insisted I take some classes with a "pro," and he insisted I dump the lefty club bag, and get a set of rights... My game really really sucked after that.
I shoot rifles right handed. My favorite rifle was right bolt, left port so I could feed it with the left side. In handguns, I mostly shoot, and carry, right side - I am right-eye dominant. But back when I had money to burn, I taught myself to two-gun point shoot.