MacAsm

Yes.

What is this useful for?

Do you use NoScript in everyday? I think while it would make those annoying APIs go away, the web site experience would became a bit poor and even not work properly.

but I make a point of putting things in his left hand.

Don't even do that. It can make he use his left hand because you're someway influencing he and if he start writing with non-dominant hand because this he may develop a lot of problems on brain.

it's a lifestyle choice.

What?! You first said there is certainly a genetic component then it's a lifestyle choice? it isn't.

my parent are right-handed too but my grandma is leftie. But it seems almost everybody else didn't have any leftie in the family that they're he's aware of. I find this odd, mostly because they says it's genetics so a lot of people cary left handed genes but it's hardly "primary"/"used" (I don't know the right word).

It would be really nice. The closest we have, so far I know, is Cygwin (I don't what it's like now, I used it a long time ago)