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.
One of the early and very famous AKC registered Staffs was Pete the Pup, (real name Lucenay's Peter), dog star of the original Our Gang comedies of the 1930's. Although the early ancestors of this breed came from England, the development of the American Staffordshire terrier is the story of a truly American breed.