Male and female hair thins for a number of reasons. Genetics contribute to how much you lose and when you lose hair. Illness or medication may cause hair loss. Poor diet or stress may also be contributing factors. Vitamin intake is extremely important in maintaining healthy hair. Additionally, if you’ve just had a child, you may experience post-partum alopecia, a condition in which the new mom’s hormones drop and she experiences some hair loss.
Hair thinning and hair loss may be due to poor nutrition, use of medication or medical treatments, hormonal changes or harsh chemicals during hair treatments. Alopecia is the general term which relates to thinning of hair and hair loss. Look here for more information: http://www.mayoclinic.com/health/hair-loss/DS00278/DSECTION=causes.
Here is a lot of reasons: stress, genetic reasons, bad nutrition (you need vitamins), hormonal changes, some diseases, therapies (chemotherapy for example) or medications. Use that home remedies for hair growth from http://www.hairgrowthmagazine.com/home-remedies/ and you will see results very soon.