A misleadingly simple view of health is calling it the absence of illness. Better to view health as a matter of degrees on a scale, the same way we measure temperature. Each organism has evolved under certain circumstances, and can operate more or less efficiently only within a compass of environmental conditions. Humans need oxygen, and are not able to live in oceans, as can whales. A cactus won't live long in a rain forest. Thus I say that the largest conception of health is at a species level. When one views health at the individual organism level, the matter becomes greatly complicated.
Every human is born with genetic programming that affects not only appearance, but functional abilities as well. A person can be born with a club foot or with a chemical imbalance. This underscores society's need to educate expecting mothers to do everything possible to ensure healthy babies. Pregnant women can cause their offspring lifelong harm by overconsuming alcohol or other drugs.
How children grow up will profoundly affect their health as adults. It has been proven by social scientists such as anthropologists, that upbringing and environment are more important than genetic differences. This, of course, is a generalization. Translated, it means we could randomly select 50 babies from widely scattered places on Earth, and raise 25 of them as if they were wolves, and 25 with nurturing, love, education, and then it would be patently obvious how much cultural influences overwhelm genetic predilections. We might summarize by saying genes allow a vast range of behavior, but culture is what shapes, selects, and lets blossom certain traits to the exclusion of others. Similarly, if children are raised undernourished, and are kept unexercised, their health will be much worse than if they are given proper or ideal conditions. It must be understood clearly what is inherited, and what is controllable. Baldness, body build, and certain other things are generally passed along through genes. Whether one exercises, eats a balanced diet, and controls stress, is in no sense genetic. There may be some overlap, but it is minor. I'm thinking that if a pregnant woman is a drug addict, so will be her child. Yet this is physiological and not technically a matter of genes.
