Can Nikon D3100 shoot good portraits?

I'm planning to buy a Nikon D3100 kit (Nikon AF-S VR DX 18-55mm lens). Along with outdoor nature photography, I'm also interested in taking portraits of my family and my kid. Will Nikon D3100 good results in portrait photography too?

Yeah, it will.

Yes, the key to good portrait photography is the lens and the light. Your Nikon D3100 will do just fine if you use the right lens and good light. Learn as much as you can about photography, with a photography course and at least use the online tutorials, like this one
http://www.geofflawrence.com/photography_tutorials.htm

Any DSLR will be pretty good at ANY type of photography, with a few exceptions. What really matters is the lens that you choose to do that type of photography.

the kit lens will provide pretty good portrait capabilities, but to get a very nice, shallow Depth of Field (meaning the distance in front of, and behind the subject that is in focus), you might want to get the Nikkor 50mm f/1.8G or f/1.4G lens- perfect for portraits

Sure, just get a portrait lens.

The new AF-S 50MM F1.8 would be nice for your portrait works. If I will buy a new prime lens, it will be my top of the list.

Its not so much of the camera body but more of the lens that makes a good portrait picture. As most people have stated earlier the nikon 50mm f/1.8G would be a great choice. "The nifty fifty"