FamilyTreeDNA is a division of Gene by Gene, a commercial genetic testing company based in Houston, Texas. FamilyTreeDNA offers analysis of autosomal DNA, Y-DNA, and mitochondrial DNA to individuals for genealogical purpose. With a database of more than two million records, it is the most popular company worldwide for Y-DNA and mitochondrial DNA, and the fourth most popular for autosomal DNA. In Europe, it is the most common also for autosomal DNA. FamilyTreeDNA as a division of Gene by Gene were acquired by MYDNA, Inc., an Australian company, in January 2021.

A genealogical DNA test is a DNA-based genetic test used in genetic genealogy that looks at specific locations of a person's genome in order to find or verify ancestral genealogical relationships, or to estimate the ethnic mixture of an individual. Since different testing companies use different ethnic reference groups and different matching algorithms, ethnicity estimates for an individual vary between tests, sometimes dramatically.