Causes of thinning hair can be explained m ore readily if we understand the basic construction of hair.  Your hair is made of a protein named keratin.  There is a hair shaft, a root that is in your scalp, and a follicle.  The follicle is where the hair root is produced.   The follicle contains the hair bulb.  The bulb is responsible for producing the pigment for your hair.
Everyone experiences stages of hair activity.  Hair can exist in one of three stages.  It can be growing, at rest, or falling out.  This is a natural process that occurs throughout our head at different times.  When the growth stage lags and the falling stage is more prevalent, you will experience that as a root cause of thinning hair.
When we look at what causes thinning hair based on our understanding of hair growth and loss as part of an elaborate organic chemical process, we can assess our daily habits and uncontrolled life events to see which ones may be legitimate.
For example, there is a myth that indicates that masturbation causes hair loss.  If you believe that, you may also believe the myth that it will make you go blind.  Seriously, though, life events and choices that affect your overall body chemistry; like stress, nutrition, drug use, pregnancy, medication, and illness are much more likely to be thinning hair causes.
Causes of thinning hair, once uncovered, can give you clues about how to fix the problem.  Some are easy to spot.  For example a prime cause of thinning hair is over styling with too much heat, harsh chemicals, and/or too much twisting or braiding.  There isn’t a quick fix for this damage, but there is hope for improvement.