A pedigree chart is a diagram that shows inherited genetic traits for generations of a family. Researchers read the data in order to determine relationships between dominant or recessive traits for individuals on the chart.

Genes come in pairs with one part from each biological parent, which is how parents transfer their genetic traits, such as physical characteristics and diseases, to their offspring. Some traits are dominant, meaning they are always expressed, even if they form only one part of the gene. Other traits are recessive, meaning they are expressed only if both parts of the gene are identical.

Pedigree charts map the transfer of genetic traits through the various generations of a family. The charts resemble family trees, with tiers describing the position of individuals with families. For example, the first tier may be grandparents, the tier below may represent parents and the lower tier may represent children.

Researchers can use pedigree charts to follow the path of dominant and recessive traits through the generations to determine those affected by genetic characteristics, those who only carry the genes and those who are unaffected. One practical use of pedigree charts is in deducing whether a child may be affected if both parents are carriers of a disease.