The first problem with classifying asthma as a genetic disease is that, it is a poly-genetic disease. It is not a single gene that is responsible for causing this disease but a cluster of genes. Dr. Jian Zhang published a research paper in this regard in 2008. He identified up to 62 genes that may be responsible in some way or other for causing asthma. Now all these genes may not pass from parent to the child but there is high probability of at least some of these genes to pass to the next generation. Thus, having asthmatic parents increases your predisposition towards this hereditary disease.
Allergic Asthma: Are Allergies Inherited Too?
Most doctors will tell you that allergic bronchitis is not genetic in nature. However, atopy is a hereditary disease. Atopy is basically a tendency to develop allergies or immunological reactions to certain allergens (things that trigger allergies). In case of asthmatics, allergies are often respiratory ones. That is, instead of developing rashes or itchy feeling, you develop spasms. This happens because inner linings of your respiratory organs like nose, throat and lungs swell up when they come in contact with the particular allergens.
Some families have a tendency to have allergies that are common like allergy to peanuts, dust and pollen.
What Are The Odds?
Just a genetic predisposition to asthma will not make you prone to asthma attacks. Environmental factors play an equally important role in fostering asthma attacks. Suppose you have genetic asthmatic tendencies but you live on a hill station and breathe in pure air. Your chances of developing a chronic respiratory disorder are very less.
If one of the parents are asthmatic then there are about 15 to 20 per cent chances that the child may have asthma. But if both parents have asthma or one/both parents are smokers, then the chances increase to about 50 percent. The remaining 50 per cent always remains with the environmental factors.
So, we can say that asthma is a genetic disease but it gets triggered by environmental factors.