- Arachnophobia, the fear of spiders, is one of the most common phobias and can be an irrational fear that affects people's lives. It causes physical symptoms like rapid breathing and nausea when one sees a spider. - This phobia has been found to potentially have hereditary factors and can be passed down from fathers to sons. While some fear of spiders is normal, arachnophobia becomes a problem when the fears are intense and interfere with daily life. It can be treated with psychological therapy.