Family inheritance
You inherit genetic markers in the same way as the rest of your DNA, half of them from your mother and half from your father. If a marker and a gene are close together on the chromosome, they usually are inherited together.
Inheriting a risk marker is different from the classical genetics you might remember from school. Some diseases have long been known to be caused by single genes. If you get the gene for cystic fibrosis, sickle cell anemia or Huntington's disease, you will get that condition. Complex conditions like diabetes and heart disease are different. They are caused by multiple genes, along with non-genetic factors, and chances are that you won't inherit all of those genes from your parents. Just because one of your parents has heart disease, for instance, doesn't mean you will inherit the genes that contributed to it.
The bottom line for your parents, children and siblings is complicated by the number of genetic variations and environmental factors involved in complex diseases like diabetes and cancer. Often, specific combinations of these markers are necessary to strongly predispose you to disease, which further clouds the ability to determine whether your family members are at increased risk.
If you have a marker that raises your risk of colon cancer:
- at least one of your parents has that marker and gave it to you.
- your siblings might, but might not, have inherited that marker from your parents.
- your children might, but might not, inherit that marker from you.
