Translation:My brother has always known how to cook.
This points out an interesting question about уметь - being able to in the sense of knowing how to is not the same thing as being physically able to do something. All evidence aside, it could be that all babies know how to cook from conception, even in the womb, but are not physically able to for obvious reasons.
Знать, как готовить means you understand the theory of cooking, but it doesn't mean you actually "know how" to cook - that you have to crack the egg before you put it on the skillet for instance. But уметь готовить means you know to turn the stove on and when to take the egg off so you don't burn your omelette >_>.
But does уметь also mean being physically able to do so?
Stephen Hawking, for instance, could both know the theory of and the practical principles of cooking - but he couldn't actually do the cooking.
So, does уметь signify not simply knowing the things that need to be done - knowing how to do something - but also being physically able or capable of doing them?