The genetic analysis of malformations enables us to distinguish four groups of different anomalies: 1. Chromosomal disorders (gene and chromosome mutations). 2. Single (monogenic) hereditary anomalies and malformations (gene mutations: point-mutations). 3. Malformations with polygenic multifactorial basis (combination of genetic and exogenous factors). 4. Exogenous non-hereditary malformations. We were able to classify malformations in one of the four groups using the three most important methods of human genetic investigations: (a) chromosomal analysis, (b) family investigations, (c) twin method. These methods can complement each other, but each has its own individual place. This review quotes examples of the four different etiological groups in otology, especially those affecting parts of the ear as well as those affecting whole ear.