How to get my photos to look like this?

I know this is probably the opposite of what most people want, but I want my pictures to be a bit darker and have this kind of noise/graininess. I have a Nikon D3100 (DSLR), I don't know if that matters. Do I need a different lens? How can I achieve this look? I don't really want to edit my pictures to make them look like this, so please don't suggest any edits.

Use the camera on your phone.

Underexpose them in camera, use a higher ISO, or darken them and add grain in a decent editing program. It is not difficult to get this look. Alternatively, you could shoot on grainy film stock.

All of these shots were taken with indirect natural light.

You should be able to see them just like this in your camera viewfinder.

Expose for the subject matter you want properly exposed and let the rest (light the windows) overexpose and the shadows fend for themselves.

Noise is generated when using high ISO settings on your camera

Your 18-55 mm lens will frame your shots like those, you just have to look through your cameras viewfinder when you compose the shot to add or remove parts of the scene as you see fit.

If you examine the images at 100%, you will see which part of the scene shows the detail and what is either overexposed (highlight with NO detail) or underexposed (shadow with little or no detail) and you should see now the lighting was used.

The shot of the child could have been shot using high speed film, thus the actual grain in the shot or someone used an add-on program like those from onOne and Topaz Labs to add the grain to mimic various types of grain found in a number of different films.

At least two ways are possible…

Simply expose for the brighter areas, such as the windows where the light is coming in, then the foreground and subjects will be underexposed.

Or set the exposure for something in the foreground, and stop down a couple of extra stops

Noise is caused by using high ISO (film or sensor), or can be added in post processing. I can't tell which method was used in these photos, since some of the EXIF data is missing. Although the EXIF says the camera that took them was a Zeiss Ikon ZM - which is a 35mm film camera.

Use a high ISO for grainy looks.
Under expose by a bit; experiment with half to 2 stops.

" I don't really want to edit my pictures to make them look like this, so please don't suggest any edits."
Problem is that they WERE edited to look like this.

If you want to try to get this look purely in camera you'll need to shoot at your highest ISO to get the grain and set your shoot style in camera to increase contrast. Then you'll need to shoot at a ridiculous shutter speed to deal with the high sensitivity.

That's the closest you'll be able to get without editing.

Switch your camera to manual mode, and have the ISO (light sensitivity) really high, like at least 800-1600 (this will make the image grainy) at the least, and make the shutter speed really fast (depending on the light in the room) to make the image darker. You could also try an aperture that is less wide, so more of the image is in focus while you are further darkening the image. A combination of these things will probably get you the results you want.

1 These photos are shot indoor, so they're lack of lights, it will be more noisy points in the photos.
2 if you wanna make your photos like this, you can get it more sharpen to looks like lower exposure.

Just set up a small aperture to you Nikon.

BTW， you can also make the style after shot. On Fotor http://fotor.com/ you can do basic edit to sharpen you photos.
more, you can add such vintage filters or in-door scene to achieve it.