The biochemical base for people\'s personality

After reading biochemical science here and there and some psycology books, I start to think there is a biochemical base for people's personality. After the first google try, I actually find something with the exact name "Biochemical Personality". They are related to drug or alcohol abuse.

http://www.narcononrehab.com/english/Narconon_Program.html

Long-term alcoholism and drug addiction can cause one's personality to change. This is called the Biochemical Personality. Some of the characteristics are:

• Mood swings
• Unreliable. Unable to finish projects.
• Unexpressed resentment and secret hatreds.
• Dishonesty. Lies to family, friends, employers.
• Withdraws from those who love him. Isolates self.
• May appear chronically depressed.
• May begin stealing from family and friends.

Addicts cannot stop using drugs for two reasons. These are:

• Cravings caused by drug residues which remain in the body.
• The Biochemical Personality caused by drugs and the lifestyle of the addict.