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.
The Staffordshire Bull Terrier is a tough-looking character. The dog is relatively wide and slightly longer than tall, giving it a low center of gravity. Most striking of all, however, are the huge muscles and wide jaws. This dog is the picture of power, yet it is surprisingly agile and quick on its feet.