Health, illness and genes
Genes affect our chances of having several common illnesses, like heart disease, asthma and diabetes but so do many other factors, such as diet and lifestyle. It is like betting on a horse race - the horse, rider, course and weather can all affect the outcome in a way that is hard to predict. Many genetic and non-genetic factors affect our health, but scientists don't yet know what they all are, or how they interact with each other.
