The advancement in technology and proliferation of research has led to the identification of genetic association for many diseases and behaviors which often lead people to believe they are at high risk for these conditions because of their family history. Learn more about how one’s genes and family history can influence one’s health.

What are Genes? 

Genetic Influence on Health

In the middle of the 19^th century an Austrian scientist named Gregor Johann Mendel observed that organisms inherit traits through discrete units of inheritance, which are now called genes. Organisms inherit traits which are genetic information carried in genes that correspond to regions in one’s DNA molecules.

Organisms have thousands of genes and these genes generally behave independently of each other and interact with each other to modify resulting traits.  Complex traits therefore are products of many genes. The degree to which these genes contribute to the formation of complex traits is called heritability. This implies that traits are not totally dependent on genes because heritability is variable and can be affected or modified by environmental factors.

The Influence of Genetics on One’s Health

To put things in more simple terms, although our genetic make-up has something to do with our skin color, our height, our predisposition to certain diseases and so on, the interaction of these genes with other genes and with the environment has greater influence on one’s over-all health.

In fact, according to research, purely hereditary diseases are very rare (1 in 2300 births for cystic fibrosis, 1 in 3000 for Duchenne’s muscular dystrophy, and 1 in 10,000 for Huntington’s disease) and account only for a small fraction of overall disease. Although some diseases seem to run in families such as breast cancer, hypertension and heart disease many family members with the genes do not actually develop the disease or are mildly affected. Even behaviors like alcoholism and chronic smoking have been found to be associated with a positive family history but these are traits that can be modified and do not absolutely predict demonstration of the behaviors.

Family History vs. Environmental Factors

One’s family history for a trait, condition or disease may be a predisposing or risk factor for one developing certain characteristics but we must also remember that medical history is not the only thing that is shared within a family or race. For instance, factors like socio-economic status, habitation, diet, cultural factors and such are shared by members of the family and these can strongly influence their risk for infections, cancer, certain social behavior, etc.

Furthermore, access to health care is another important factor in the outcome of health, so that disadvantaged families or groups will have poorer outcomes leading to more serious consequences or death.

Genetics vs. Lifestyle Factors

We now know that many chronic diseases like diabetes, hypertension, cancer and even psychiatric and developmental conditions like autism and Alzheimer’s disease are hereditary. However, genes are able to cause disease only up to a certain extent.

It has been found that one’s lifestyle can interact with one’s genetic background and that lifestyle changes can alter the effect of genetics.  For example, the incidence of hypertension is high among those who have parents or grandparents who have the condition. But the risk increases with:

• People who smoke
• People who drink alcohol
• Women who take oral contraceptives
• People who are obese and sedentary

On the other hand, the incidence of the disease decreases with people who maintain a healthy lifestyle in spite of a positive family history.

What We Can Do

More research may be needed to identify the specific genes that interact with each of the behavioral traits and environmental factors to know the relationships between them. In the meantime, although there is very little one can do to change their genetic background or modify our family’s medical history, people have to be educated on things they can control and have more impact on their health, such as:

• Maintaining a healthy lifestyle through good diet and adequate exercise
• Creating public policies for disease prevention such as the need for certain vaccines, screening tests, etc.
• Acquiring sufficient access to health care
• Proper education on health practices
• Avoidance of unhealthy habits like smoking, heavy drinking, drug abuse, etc

References

BMJ, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC403856/

Main Line Health, http://www.mainlinehealth.org/diw/Content.asp?PageID=DIW009777&More=DIW