Is asthma hereditary? This is a question of great concern to many patients. The close relationship between asthma and heredity has been confirmed by numerous studies. Asthma epidemiological surveys show that 54% of asthma patients have a positive family history of allergies and 42% have a history of asthma. Twin surveys also show that monozygotic twins have a higher incidence of asthma than dizygotic twins. Asthma is generally considered to be a polygenic genetic disease with a heritability of 80%. However, by no means does it mean that if a child has asthma, both of his or her parents must also be asthmatic. The more closely related a child is, the higher the incidence of asthma in his or her relatives. 2.