Many traits are influenced more by environment rather than heredity. Some of these traits include behavior and attitude. Besides being influenced by heredity, these are also influenced by who you are around, such as family, friends, school, neighborhood, and social environment. The dictionary definition of heredity is: the transmission of genetic characters from parents to offspring. The definition of environment is: the aggregate of surrounding things, conditions, or influences.
It is important to try to determine the relative influence of heredity versus environment because for example, two biological siblings, born into the same social and family environment, and by the same biological parents, may act completely different, one may be very socially outgoing, while the other is much more shy and socially reserved. Also, one child has a learning disability, while the other performs extremely well. This is also important medically because if you have to treat a certain condition, you usually want to know if that problem is a hereditary disease, especially if that disease is lethal, so that you can alert children of the victims and possibly have them tested for it. However, environmental diseases are important to define as well. These can be almost as bad as the hereditary diseases, due to the fact that you could pick up one of these diseases just by living in a certain area.
This could be very problematic if doctors and scientists do not know if the specific disease is from the environment, because there could many, many people in that area that could all be infected with this disease very quickly, first causing an epidemic and then possible spreading it yet still, causing an epic pandemic. Some diseases, however, are actually both hereditary and environmental. For example, at one time , HIV was completely environmental, however, now it is also hereditary.