"Genetics": When changes happen in a person's genes (called "mutations") these changes are passed on to their children. One or both parents may have these changes or "mutations" in their genes, and some or all of their children may be born with them, which means they "inherited" them. These mutations, once they happen, run in families from one generation to the next and are permanent mutations, they change the gene in the "DNA". These changes can make a person more likely to get certain diseases like asthma. In some diseases it may be only one change in one gene that may make a person get that disease, in asthma it may be changes in many different genes that may make a person more likely to get asthma.