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Mid-Cities Genealogical Society
DNA Vocabulary
Admixture: See Ethnic Origins
Autosomes: The 22 nonsex chromosomes within the nucleus of a cell
atDNA (autosomal DNA): One type of DNA used in genetic genealogy that utilizes the 22 nonsex chromosomes
Base Pair: Two complementary bases located on opposing DNA strands; see nucleotide
Centimorgan (cM): A unit of measurement for DNA segments. Generally, the more cMs shared between individuals, the more genetically “related” they are. A DNA shared cMs chart can be very helpful in identifying possible family relationships, based on the number of cMs of each individual.
Chromosome: A strand of DNA within the nucleus of a cell that carries genetic information
Chromosome Browser: A feature offered by some genealogy companies that allows you to view matching segments on a visual map of the chromosomes
Chromosome Mapping: The process of assigning ancestors to individual DNA segments
DNA (deoxyribonucleic acid): The genetic code that defines each individual’s biological characteristics
DNA Project: A group of people whose DNA or surname indicates a biological connection; project administrators for DNA projects are knowledgeable and group the DNA results of group members
Endogamy: The practice of limiting marriage to members of one’s specific social group (such as tribe, community, ethnic group); using DNA within an endogamous group becomes more difficult
Ethnicity estimates: Approximate amounts of DNA inherited from various ethnicities based on a comparison between your DNA and reference samples; DNA testing companies report ethnicity estimates differently
Genetic Genealogy: The use of DNA test results to establish or confirm genealogical relationships
Genetic Genealogy Standards: Ethical and usage standards in using DNA established as guidelines for genealogists and others. See
Haplogroup: Group of similar haplotypes that share a common ancestor identified by a single, well known mutation
Haplogroup Project: A project consisting of those who share a common haplogroup
Haplotype: A group of alleles that are inherited together, also known as a genetic signature
IBD (identical by descent): A segment of DNA that is found to be identical (except for rare mutations or testing errors) in two people who are related to each other due to the fact that this segment was passed down to both of them from a common ancestor.
IBS (identical by state): A region of the genome where two people share at least one matching allele for every allele reported (allowing for possible mutations or testing errors)
ISOGG Wiki: A reference wiki built and maintained by the International Society of Genetic Genealogists; see
Match: Individual identified by a DNA company as having shared segments of DNA
Mitochondria: Located in the cytoplasm of a cell, the mitochondria are the cell’s powerhouses
MRCA (most recent common ancestor): The most recent ancestor (or ancestral couple) that is shared by two individuals
mtDNA (mitochondrial DNA): DNA associated with a cell’s mitochondria, passed down from mother to child
Mutation: A change in a person’s DNA
NPE (non-paternal event): When the parent identified through paper trail research is not the biological parent
Nuclear DNA: DNA located in the cell’s nucleus; These include the 22 paired autosomes and the sex chromosomes, making 23 pairs in all
Nucleotide: The basic building blocks of the DNA molecule; The 4 known nucleotides are adenine (A), guanine (G), cytosine (C), and thymine (T)
Paper Trail: Genealogy done by researching traditional records such as census, probate, vital, etc.
Phasing: The process of discovering which allele data was contributed by each parent
Surname Project: A project researching the genealogical origins of persons with a given surname
Tree Triangulation: The process of proving a genealogical relationship by showing that 3 (or more) individuals independently share a paper trail and inherited DNA from a common ancestor
xDNA: One of the 2 sex chromosomes; individuals with 2 X chromosomes are female; x chromosomes have a unique inheritance pattern because an X chromosome cannot be passed from father to son
yDNA: One of the 2 sex chromosomes; individuals with a Y chromosome are male; yDNA is passed from father to son