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.
They are extremely strong for their size. American Staffordshire terriers have a medium sized muzzle, and it is round at the upper side. Their eyes are dark and round and the lips are tightly closed, but there is no looseness or dewlap. This dog breed has a thick, glossy, and short coat of fur.