dnaof() - inheritance made easy, my own make inheritance tool
From a once over, and borrowing from the comments:


__proto__ is bad news, MDN mentions this in a big red box of doom.
There is no means to pass parameters to the constructor, that does not make it simple
X, x, k, r and p are terrible variable names
dnaof is an unfortunate name
lowerCamelCase is good for you, kindof -> kindOf, 
You can get the parent class thru Object.getPrototypeOf(Object.getPrototypeOf(this)) in dnaof
I have mixed feelings about the can trick. It is shorter than typing prototype, but it's also a candidate for nameclashes.
You have no comments at all in your code, combined with 1 letter variables that makes for not good code
If I were to build an OO library, I would also play with constructor and add some support for private.


All in all, this is something I would not mind using, but that I would hate to have to maintain.