In 1916 Robert Cooke and Albert Vandeveer demonstrated the role of heredity

Heredity

Heredity is the passing of traits to offspring . This is the process by which an offspring cell or organism acquires or becomes predisposed to the characteristics of its parent cell or organism. Through heredity, variations exhibited by individuals can accumulate and cause some species to evolve...

 in the origins of allergy

Allergy

An Allergy is a hypersensitivity disorder of the immune system. Allergic reactions occur when a person's immune system reacts to normally harmless substances in the environment. A substance that causes a reaction is called an allergen. These reactions are acquired, predictable, and rapid...

. According to Cooke, 48% of his allergic patients had allergies in their family history

Family history (medicine)

In medicine, a family history consists of information about disorders from which the direct blood relatives of the patient have suffered. Genealogy typically includes very little of the medical history of the family, but the medical history could be considered a specific subset of the total history...

. While the trait of allergy is transmitted through heredity, parents and children may be allergic to different substances.

In 1918, Dr. Cooke suggested a mechanism of action for allergen injections as a "desensitization

Desensitization

Desensitization can refer to:* Desensitization * Desensitization * Desensitization * Desensitization of explosives, see Phlegmatized...

 or hyposensitization," analogous to tolerance achieved in experimental anaphylaxis

Anaphylaxis

Anaphylaxis is defined as "a serious allergic reaction that is rapid in onset and may cause death". It typically results in a number of symptoms including throat swelling, an itchy rash, and low blood pressure...

 induced in animals. This concept suggested that the injections of an increasing amount of allergen or antigen

Antigen

An antigen is a foreign molecule that, when introduced into the body, triggers the production of an antibody by the immune system. The immune system will then kill or neutralize the antigen that is recognized as a foreign and potentially harmful invader. These invaders can be molecules such as...

 slowly neutralized those antibodies responsible for the allergic reaction.