Principles of Inheritance and Variation — BIOLOGY STD 12 Science — Question

Hereditary disorders are prevalent in human society and this has been heard since ancient times that some traits are hereditary. After the rediscovery of Mendel's work, the practice of analysing inheritance pattern of trait human being began. Since it is evident that control crosses performed pea plant and some other organisms are not possible in human being. Therefore, in relation to hereditary disorders, there is only one way to study the history of the lineage in relation to the inheritance of a particular trait. Such an analysis of trait, which continues for several generation is called the pedigree analysis. In the pedigree analysis, the inheritance of a particular trait is represented in the family tree over generation.
In human genetics, pedigree study provides a strong tool which is utilised to trace the inheritance of a specific trait, abnormality or disease by genetic counseller.