Comment I recommend whatever your Brother is interested in (Score 1) 799
I am a self-taught programmer and I have been programming for over 12 years. I started my interest in programming when I was 12, but wouldn't consider myself into programming until I was 14.
When I was 12, I got a C++ programming book and went through it fairly quickly. My interest was in developing video games like Doom, Quake, etc. At the time I was young and lacked the knowledge or dedication to look into this any further and became attached to HTML/JavaScript, PHP and AS2/3 as a web developer and 2d/3d animator/modeler/artist.
Slightly off-topic bg info: I actually went to school for Media Arts and Animation(Where I flunked out with 1 class to graduate due to financial issues and turned to programming permanently) and while I did take a couple minor programming courses based on AS2, I found that I already knew more than the teachers at my school on the subject from reading through the docs when I was 15-18 and ended up serving as a tutor in the classes(as I did in virtually all classes with nearly straight A's and still unable to graduate from final class, almost laughable if it hadn't cost so much) even though I would now consider my knowledge of AS2 at the time to be infantile. I should have expected as much since the school was dedicated to art students, many of whom could barely work a computer.
Back to the subject: I think the best way to get a new person into programming would be to teach them the fundamentals of object oriented programming first and make sure that it is taught around something they are interested in. For example, if the noobie is interested in games I would suggest teaching them to program in UnrealScript - Unreal Engine 3 - UDK or XNA Game Studio 3.1. If he is into 2d graphics and animation try AS3 or Silverlight(I do not really have experience with Silverlight past a few documentation glimpses and tutorials). If he just likes dealing with data try PHP/MySQL.
The important thing here is to make sure that he grasps the techniques needed to produce reliable, extend-able, clean and well documented object-oriented code. If he's really interested in programming he's probably already good with math and will pick up on the algebraic and geometrical side of things easily in school math classes and be able to relate them to the object-oriented ideas you have already instilled in him allowing him to be able to generate code producing quick visual results with any of the previously suggested packages. All of the languages I have suggested are extremely well documented.
I hope I have been helpful.