Sometimes it really is all in the genes. Knowing your family's medical history can alert you to potential problems and help you take precautionary measures. As researchers discover new genetic markers, certain individuals and families may be identified as having a higher than average risk for a variety of diseases. When it comes to your health, the apple does not fall far from the tree. Knowing your family medical history may save your life or the lives of your children and grandchildren.

"We already know family history is an important risk factor for several cancers," says Robert Dalton, MD, a hematologist/oncologist with St. Mary's/Duluth Clinic Regional Cancer Center in Duluth, Minnesota. " Breast, colon, thyroid, ovarian, and prostate cancers commonly run in families. In some cases, a family history of one of these cancers puts you at higher risk for the others."

Pick your poison. Heart disease, stroke, asthma, diabetes, arthritis, and Alzheimer's all tend to run in families. You will not necessarily be affected just because someone else in your family was, but under certain circumstances your risk might be increased. Inherited risk involves complex interactions among several genes and your environment. Your behaviors—smoking, weight management, dealing with stress, heavy drinking, exposure to toxins—influence whether you'll get a disease.

Sleuthing Your Family Medical History

Your family medical history is valuable to you and to future generations of your family. Medical histories for your first-degree relatives are most important. First- degree relatives include:

• Parents
• Brothers and sisters
• Children

You probably already know a lot of your family medical history. For the rest, talk to relatives. They may be more open to discussing dates of diagnosis and causes of death if you explain the good deed you are doing for the whole family. Dig through old medical bills. Death certificates are available at your county records department for a reasonable cost. To request a medical record from a hospital or doctor, you must have written permission from the person whose record you want. If they are deceased, you must get written permission from the closest living relative.

How to Create a Family Medical Tree

Researching your family medical history is like genealogy. You can keep it simple or get completely carried away. Collect medical histories for your first-degree relatives, this information includes:

• Date of birth
• Date of death
• Cause of death
• Major illnesses or surgeries
• Date when major illness was diagnosed

If you can, collect the same information about your second-degree relatives:

• Grandparents
• Aunts and uncles
• Nieces and nephews
• Grandchildren

As you build your family medical tree, remember these tips:

What Does It All Mean?

Here are a few general guidelines for interpreting the medical information of your relatives:

• The more generations an illness occurs in your family, the more at risk you are.
• Two or more first-degree relatives with the same or related cancers suggests an inherited risk. For example, if you have two first-degree relatives with ovarian cancer, you have a greater chance of getting it yourself. Keep in mind breast, ovarian, uterine, and colon cancers are genetically related.
• The younger someone is when a disease develops, the more likely heredity played a role. If your mother or sister developed breast cancer before menopause, your lifetime risk is higher than it is for other women.
• A disease that strikes two or more relatives at about the same age is likely to be strongly influenced by heredity.
• Clustering of cases of the same disease on one side of the family more strongly suggests a genetic influence than if a similar number of cases are scattered on both sides of the family.

What If You Are at Risk?

If you suspect you are at risk for a "family disease," show your doctor your family medical history. Your doctor may suggest you undergo screening exams sooner than is normally recommended.