Some professionals have indicated that phobias may be based on conditioned emotional experiences. These experiences can be derived from a traumatic experience within one’s past.
Alternatively, others believe that phobias may be caused biologically through evolution. In this case an individual develops natural fears to things such as spiders and snakes.
Some phobias can also develop from a previous phobia. An individual purchasing ice cream, as a child, from an ice cream truck may have been nearly hit by a car. This child may have developed a phobia to ice cream, then milk, and all dairy products. This individual could have also developed a fear of driving a car, crossing the street, or riding on buses.