Frequently Asked Questions

Q. Many of my family members are not available. How can I collect my family health history?

A. In most families, not everyone is available. You may have family members that are deceased, living elsewhere, or just not interested in participating. Use what you have, keeping in mind that the fewer family members you have, the more important each one is. Also keep in mind that each person’s genes come from the birth mother and father, even when new family relationships are made later. A person who was adopted may not be able (or may not wish) to access information; in this case, an adopted person’s own health history is especially important, since it is the beginning of a new story.

Q. Where can I find more information about the health problem that runs in my family?

A. If you are seeking medical advice, start with your own healthcare provider. Your provider may be able to answer your questions and recommend a course of action. If you or your provider are seeking additional healthcare resources, you may find what you need through the websites on our Links page. There, we have listed many of the sites that we use and trust.

If you wish to use the internet to learn more about your condition, you need a strategy to find information that is credible. A good strategy is to begin your search with websites from the US Government, including the Centers for Disease Control & Prevention and the National Institutes of Health. For specific guidelines, see MedlinePlus: Guide to Healthy Web Surfing or the "Trust It or Trash It" tool from the Genetic Alliance.

Q. When I learned genetics in school, I learned about Punnett squares and, also, dominant and recessive traits. How do “risk genes” and “genetic risk” relate to what I learned in school?

A. The genetics you learned in school most likely focused on the work of Gregor Mendel. In this traditional view of genetics, one gene determines one trait. A person has two copies of each gene, with one copy coming from each parent. Since every gene comes in different forms, a person can have two gene copies that are identical to each other or two gene copies that differ. A diagram called a Punnett square provides a way to follow the segregation of genes from each parent and to predict all possible combinations of genes in the offspring. By knowing if a particular trait is dominant or recessive, predictions can be made about the presence or absence of the trait in the offspring. One important exception is segregation of the genes located on the X and Y chromosomes. This is because X and Y chromosomes differ in females and males. If you would like to learn more about Mendelian genetics, look at some of the sites on our Links page.

As knowledge about our genes has expanded, our understanding of the genetic basis of health problems has become more sophisticated. It has become clear that the relationships between our genes and our physical traits (including our health) are complex. Sources of complexity include the following:

• There is a lot of potential variation within any one gene. This means that there are many possibilities for the specific makeup of the two copies of a gene that a person has.
• In normal gene function, there are lots of interactions between genes. This means that how a gene functions may be influenced, not only by its own genetic makeup, but also by the genetic makeup of other genes in its network.
• In addition, gene function can be affected by many outside factors, such as medications, food intake, and exercise.

The different versions of a gene can exert different effects. Some changes in a gene are sufficient to cause a disease on their own. Other versions cause no apparent problem or cause a problem only when other factors also are present. The term “risk gene” is used to describe one or more versions of a gene that can increase the chance of a particular health problem, especially when other risk factors also are present. Because of the complexity described above, it tends to be very difficult to make useful predictions about health on the basis of one (or even a few) risk genes. Although many of Gregor Mendel’s principles still hold true, risk genes do not fit with a simple dominant or recessive model. Our understanding of genetics has moved beyond anything that Mendel could have imagined!

Example of Punnett square: