Genetics & Your Health

Preface to Clarke Fraser's Your Genealogy Affects Your Health

Most people are interested in their family trees for social reasons - whether their ancestors trace back to somebody famous (the Frasers trace back to Charlemagne, I am told), or skeletons in the family closet waiting to be discovered. But the family tree can be interesting for other reasons too. Family resemblances, for instance - how certain facial features or behaviors run in families, and what diseases. In the last few years there has been a vast increase in knowledge of human genetics, which is greatly enlarging our understanding of what and how things run in families. People are beginning to pay more attention to the things that occur in particular families and what they mean to particular family members.

If someone in your family has a certain disorder, it is useful to know whether this puts you at risk for the same disorder, whether it can be tested for, and what can be done about it. For example, if you are predisposed to breast cancer, you may want to seek more stringent screening. If you are predisposed to early coronary disease, it is (even more) advisable to avoid smoking, reduce weight, and get more exercise. That is why your family history can be important to your health.

To help you evaluate your family history, this book will summarize what is known about the inheritance of normal human characteristics, and of the common familial diseases. Only the common ones, because there are thousands of genetic diseases that are so rare that most people have never heard of them. Details of these can be found in catalogs such as OMIM (On Line Mendelian Inheritance in Man - http:/ "Common" means common enough to be familiar, as well as familial.

Advances in genetics have also widened the horizons for genealogists. The genes on the Y chromosome (which determines maleness) are transmitted only by men, and only to their sons. That means the male half of the family tree can be tracked in the DNA. If you are related to Charlemagne through males only, a geneticist could probably prove it. And there are genes called mitochondrial genes that are only transmitted to their children by women. There are already companies that will track your ancestries this way - for a price.

Chapter One of this book will present you with the least you need to know about genetics to understand the rest of the book. Chapter Two reviews what is known about the genetics of normal characteristics. These conditions are interesting even though their presence in the family does not influence your health. Chapter Three will deal with the common physical (as opposed to mental) disorders, and what it means to you if they occur in your family. Chapter Four will do the same for behavioral characteristics, ranging from personality to the psychoses.

Review your family tree, look up the conditions you find in it, and consider whether they may be relevant to your health. You may not find all that many disorders in your family, but you are sure to find some. In my family there are close relatives with Alzheimer disease, type 1 diabetes, longevity, and stroke. And you will find lots of conditions that run in your family in chapter 2 on normal traits.

Most genealogists do not record the important facts, like what diseases people had.
Clarke Fraser's Your Genealogy Affects Your Health helps to familiarize yourself with your family's history of disease, and shows what steps you can take to reduce your risk of getting a close relative's particular disorder.

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