Are Genetics Responsible for Allergies? :: Biology Essays Research Papers

Are Genetics Responsible for Allergies? A Study In Identical Twins Everyone has either suffered from some kind of allergy, or knows somebody who has suffered from allergies. Allergies are the source of irritating symptoms, ranging from a painless skin rash to life-threatening breathing problems. For years, researchers have been trying to find out the source of these allergies. Some have suggested that environmental factors or early exposure to certain foods can cause allergies later in life, while others say that allergies are caused by genetics. To test the latter theory, many researchers study identical twins to see if sets of twins share allergies. If both twins were to share a particular allergy, than this may prove that allergies are genetic. To completely understand the remainder of this essay, one must understand the difference between identical twins and fraternal twins. Twin zygosity is the genetic relationship of twins. There are two types of twins: monozygotic twins, also known as identical twins, and dizygotic twins, also known as fraternal twins. Identical twins have exactly identical DNA strands; they are same sex and they have very similar physical traits. They come from one egg that is fertilized by one sperm. Some time after conception, the egg splits resulting in two babies. Fraternal twins only have half identical DNA; that is, only one strand of the double-stranded DNA is the same. They come from two individual eggs that are fertilized by two individual sperms. They are either same sex or different sex, and are just like siblings of same parents born at different times. There are other kinds of twins as well; for example, "mirror-image twins," "polar body twins," and "half-identical twins." These names refe r to the time that the egg splits in identical twins. This essay, however, will deal with only identical and fraternal twins (5). The question now is, Are identical twins allergic to the same things? Since identical twins have exactly identical DNA, the sharing of allergies can shed some light on the role of genetics in allergies. All sorts of food allergies affect eight percent of children and two percent of adults in the United States. Allergic reactions happen because one's immune system overreacts to regular foods that are ordinarily harmless to the general population (7). An allergy affecting many children and adults recently in the United States is an allergy to peanuts. In the last few years, tremendous amounts of people have developed this allergy, which seems, in most cases, to be very severe.