It's not just serotonin either-most neurotransmitters can cause anxiety or anxiety like symptoms, and in some cases an over-abundance of a chemical can lead to anxiety. So it does appear that you can develop it without experiencing a stressful life.
Howard Heinzl (1918 - 1989) With regard to blue American Staffordshire Terriers, any breeder that believes that a blue American Staffordshire Terrier is some how more valuable than the other recognized colours, is not only deceiving themselves, but they are also deceiving their customers.
Weight Males - 57 to 67 lbs. Females - 40 to 60 lbs. Stocky and muscular with a strong, powerful head, the American Staffordshire Terrier resulted when the courageous Bulldog was crossed with a spirited, agile terrier breed. Friendly, intelligent and loyal, this people-oriented breed thrives as part of the family and when given a job to do. An excellent guardian, he loyally protects his family.