Agreement in the types of data that occur in natural pairs. For example, in a trait like schizophrenia, a pair of identical twins is concordant if both are affected or both are unaffected; it is discordant if one of them only is affected. Likewise, the pairs might be non-identical twins, or sibs, or husband and wife, etc.
Origin: L. Concordia, agreeing, harmony
a harmonious state of things in general and of their properties (as of colors and sounds); congruity of parts with one another and with the whole.The degree of likeness in a phenotype of organisms in a same species, such as people with the same colour of eyes or hair.