Susceptibility to disease, abilities, personality and other individual characteristics, or phenotypes, are influenced by genetical and environmental factors. Regarding the genetical factors (DNA base sequences: genetic polymorphism), following the rapid progress of genetics sprung by the sequencing of the human genome in 2003, the relationship between genetic factors and phenotypes is being unraveled bit by bit. It is estimated that the relationship will be understood nearly completely within the next 10 to 20 years.

Environmental factors, on the other hand, have been found to influence the expression of genes even after birth. One could think of genes related e.g. to various diseases as having on-off switches that are flipped on and off by environmental stimulus. Twin studies can be used to find out which way the switch has been flipped, so to speak, by allowing us to detect the environmental factors that determine whether an individual has a disposition for developing a certain disease or not. The same method can also enable us to negate the effects of that disposition by making an intervention to counter the influence of the environmental factors and stop the disease from ever developing. This is the realization of a happier and healthier longevity society that we strive for.