Arachnophobia is mainly learnt from our parents or peers, research shows Spiders, snakes, claps of thunder - we can have phobias about anything.
But new research has revealed that while they often run in families, that's not because we genetically inherit them, but because we learn them from our parents - scientists from Rutgers University in New Jersey, who conducted the study, have suggested.
As a toddler, if your mother screamed the first time you proudly showed her the spider you'd just found, her behaviour certainly primed you to find spiders frightening, too.
But to turn it into a full-blown phobia some other traumatic event has to happen to you, too.
Your parents, if you like, act as the phobic trigger, but it's your own traumatic experience and your unique response to it that fires the starting gun on the phobia.
When people are stressed, their vulnerability to phobias is far more pronounced because the full phobic response is the emotional and biochemical equivalent of the straw that breaks the camel's back.
The good news is that if it is true that generally phobias are learned rather than inherited - and therefore harder to treat - there are ways of tackling them. One is to teach people to reduce their stress levels by using relaxation techniques.
Another method is desensitisation which involves relaxing the patient and then gradually exposing them to whatever it is that triggers their phobia.
Hypnotherapy has been shown to be very effective at helping people cure their phobias, such as fear of flying.... or of crashing.
This places the patient in an extremely relaxed state, at which point they can be exposed to their phobic trigger.
As both the level of relaxation and the exposure to the phobic trigger is controlled, what we're effectively doing is rewriting their response to that trigger.
With simple self-hypnosis techniques, the aeroplane that once inspired blind panic can now be boarded calmly.