Nobody knows the exact cause of AMD, but there appears to be a hereditary component, in addition to those that relate to patients' lifestyle. Apart from identical twins, all of us differ in our genetic make-up; there isn't just one correct copy of the human genome. Most genetic differences are small, or subtle, and account for why we look and behave differently - why we're all individual. Occasionally, some people have genetic variants which are larger, or more significant. These changes can be associated with inherited forms of disease, such as some types of cancer, or even eye disease. The most severe genetic variants result in childhood-onset conditions, whilst milder changes only cause a problem later in life. AMD, by definition, occurs after middle age, and most commonly when patients are much older than 50 years old, so the genetic variants that contribute to it developing are milder, and so harder to find. Despite this, researchers have identified some genetic variants that are associated with a higher risk of developing AMD, however the effect of these variants cannot always be accurately predicted. People carrying these genetic changes will be at increased risk of developing AMD, but some other environmental factors also need to contribute (poor diet, smoking, lots of very bright sunlight etc). Usually it is the combination of both moderate genetic variants, and some lifestyle factors that contribute to AMD. As to whether you develop dry or wet AMD may be even more complicated, and ultimately depend upon how the individual cells in your eye respond to aging.