Congenital Causes

 
  Genes (DNA) inherited from ancestors or parents that affect breast development (low levels of female hormones); impaired foetal breast development due to excessive drinking, heavy smoking, drug abuse, etc. during pregnancy.
 
     
     
 

Acquired Causes

 
  Malnutrition, lack of sleep, smoking, drinking (too much), psychological stress, insomnia, drugs and so on.