The Wall Street Journal has a great story that tells how genealogists can even save or prolong the lives of the people that mean the most: their loved ones.
In the article, Anna Wilde Mathews writes:
Heredity plays a strong role in many health problems, ranging from Alzheimer's disease to macular degeneration and immune-system disorders like Crohn's disease. Though scientists have discovered genetic markers tied to many illnesses -- and tests have been developed to determine which patients have such markers -- these currently account for only a small portion of the risk for some diseases. That's the case with maladies such as stroke, most types of epilepsy and schizophrenia.
Many doctors say that keeping track of your family history can be a better way to gauge your risks than getting genetic tests. Family records might turn up correlations that tests can't yet fully explain.
You might want to read the entire article at http://online.wsj.com/article/SB124467618643403993.html.