Thank you for the picture! To be quite honest with you, there are a multitude of reasons why nostrils can end up being uneven - the best way to determine what exactly is the reason for them in a particular person is through a detailed history and physical exam. That being said, based on your picture, I can try and help you a little. First of all, in regards to nostrils being caused by a deviated septum - it certainly can cause it, but it is not the sole reason for it. It also depends on where the deflection/deviation is - if you have what is called a "caudal deflection/deviation/dislocation", meaning at the front of the nasal septum where it attaches to the lower cartilages, then certainly it will affect your external nasal valve as well as the position of those lower lateral cartilages which comprise part of the nostril opening and rim. That being said, as you may gather, there are different components that give the nostrils their particular appearance - the location and position of the lower cartilages (the position, appearance, etc of what is called the medial and lateral crura of the lower lateral cartilages), the position of the bone to the nose where upon they sit (known as the pyriform aperture). Long story short, there are quite a few things that go into determining nostril shape. Like I said, best way to figure out just how much of this asymmetry may be caused by a caudal septal issue is via examination. I hope some of this helps! I know I just gave you a lot of information to process! Best of luck.