DNA Encyclopedia

The molecule containing the genetic code that guides development and reproduction in all living organisms.

The full chemical name for DNA, the double-stranded molecule carrying genetic instructions.

The twisted-ladder structure of double-stranded DNA, formed by complementary base pairs.

The basic building block of DNA, consisting of a sugar, a phosphate, and a nitrogenous base.

One of the four nitrogenous bases in DNA, always pairing with Thymine.

One of the four nitrogenous bases in DNA, always pairing with Adenine.

One of the four nitrogenous bases in DNA, always pairing with Cytosine.

One of the four nitrogenous bases in DNA, always pairing with Guanine.

Two complementary nitrogenous bases (A-T or G-C) held together by hydrogen bonds in DNA.

The weak chemical bond that holds complementary base pairs together in the double helix.

The basic structural and functional unit of all living organisms, containing your hereditary DNA.

The central organelle in a cell that contains your chromosomes and nuclear DNA.

Organelles outside the cell nucleus that generate energy and contain their own circular DNA (mtDNA).

A thread-like structure of DNA and proteins carrying genetic information in the cell nucleus.

Any chromosome that is not a sex chromosome. Humans have 22 pairs of autosomes.

The 23rd pair of chromosomes (X and Y) that determines biological sex.

A specific sequence of DNA nucleotides that codes for a molecule or a functional protein.

The specific physical location of a gene or DNA marker on a chromosome.

One of two or more alternative versions of a gene or genetic marker at a locus.

The specific genetic makeup or combination of alleles at a particular locus.

The observable physical characteristics or traits of an organism, influenced by genotype and environment.

A spiral curve or shape, describing the structural form of the DNA molecule.

The complete set of genetic material or instructions present in an organism.

The process by which maternal and paternal chromosome pairs cross over and swap DNA during meiosis.

A random change in the DNA sequence that occurs over generations.

A new genetic mutation that appears for the first time in a family member.

An outdated term for non-coding DNA regions that do not produce functional proteins.

DNA sequences that do not code for proteins but contain regulatory and structural elements.

Proteins around which DNA winds to package itself compactly inside chromosomes.

The study of changes in gene expression that do not involve altering the DNA sequence itself.

A mature haploid reproductive cell (sperm or egg) containing 23 individual chromosomes.

The diploid cell formed by the fusion of two gametes, containing a full set of 46 chromosomes.

The specialized cell division that produces sperm and egg cells with half the normal chromosomes.

The standard process of cell division resulting in two genetically identical daughter cells.

The constricted region of a chromosome separating its short (p) and long (q) arms.

An individual who shares identical segments of DNA with you, indicating a shared common ancestor.

The primary unit of measurement for genetic linkage, indicating the probability of recombination.

The standard abbreviation for centimorgan, the unit of genetic measurement.

The total sum of genetic material (in centimorgans) shared across identical segments.

A continuous block of DNA on a specific chromosome shared by two individuals.

The single largest shared block of DNA between you and a match, measured in cM.

The comprehensive database dashboard showing all testers who share DNA with you.

A cousin who shares DNA with both you and another specific DNA match in your list.

A filter tool showing matches who share DNA with both you and a target match.

Most Recent Common Ancestor; the closest shared ancestor from whom you and a match both descend.

A testing platform's automated estimate of your relationship based on shared cM.

The spectrum of possible biological connections for a given amount of shared DNA.

A sibling with whom you share only one biological parent.

DNA segments shared by two or more people inherited from a verified common ancestor.

DNA segments that are identical by chance or because of common population origins, not inheritance.

Identical DNA segments created purely by random base-pair matching, not common ancestry.

The process of separating your raw DNA data into distinct paternal and maternal strands.

A DNA match that has been verified against phased parental data.

A genealogical term for when a biological father is not the documented legal/social father.

A person listed as a DNA match who does not share a true, recent common ancestor.

A DNA match sharing an identical segment inherited from a recent common ancestor.

A pattern in endogamous families where ancestors intermarry across multiple branches.

Cousins who share only one common ancestor instead of a traditional couple.

Cousins who share two distinct sets of common ancestors (e.g., sibling pairs marrying sibling pairs).

The number of mutations or differences separating two genetic profiles.

A relative who shares a set of grandparents with you.

A relative who shares a set of great-grandparents with you.

A relative who shares a set of second great-grandparents with you.

A match sharing small DNA segments, typically under 15–20 cM.

A match sharing significant DNA, typically over 90–100 cM.

Testing both yourself and a parent to confirm parentage and phase your match data.

A match representing a full biological brother or sister.

A match representing a biological sibling of your mother or father.

A match representing a biological child of your full sibling.

A match representing a biological parent of your mother or father.

A visual utility allowing you to inspect shared DNA segment locations across chromosomes.

The process of assigning specific, physical chromosome segments to documented ancestors.

The process of proving that three or more people share an identical overlapping DNA segment.

A group of three or more testers who all share the same overlapping chromosome segment.

A specific chromosomal region where your DNA matches coincide with each other.

A visual display representing different ancestral or ethnic origins across your chromosomes.

The act of using tools like DNA Painter to map your shared matches onto chromosome profiles.

Chromosomal areas where excessive matching occurs due to deep, historic population sharing.

Sharing more DNA with a match than is genealogically expected for your documented cousin tier.

The practice of marrying within a closed geographic, cultural, or religious community for generations.

When common ancestors appear on multiple branches of a family tree, reducing your ancestor count.

The genetic line tracing directly back through your mother, mother's mother, and so on.

The genetic line tracing directly back through your father, father's father, and so on.

The likelihood that a crossover event will occur between two markers on a chromosome.

A gene or short sequence of DNA used to identify individuals, species, or ancestral lines.

A single-letter mutation at a specific position in the DNA sequence.

A pattern of two or more nucleotides repeated multiple times sequentially on a chromosome.

The speed at which random genetic changes accumulate in a lineage over time.

The random fluctuation of allele frequencies in a population over generations.

Reduced genetic diversity occurring when a new population is started by a tiny group of individuals.

A sharp reduction in population size due to environmental events, reducing genetic diversity.

The statistical breakdown of your regional and ethnic origins based on DNA comparison.

The genetic mixing of previously isolated population groups over historical timelines.

A DNA match with whom you share more than one identical segment of DNA.

A DNA match with whom you share only one single block of identical DNA.

The physical gap on a chromosome browser around the centromere where DNA cannot be sequenced.

The DNA inherited on the X-chromosome, following a unique, non-traditional inheritance path.

The sex chromosome found in both males (one copy) and females (two copies).

The unique genetic path of X-DNA, which can never pass from a father to his son.

Regions on the X and Y chromosomes that can recombine with each other during meiosis.

The physical exchange of chromosomal segments between sister chromatids during meiosis.

The minimum and maximum cM values expected for a specific biological relationship.

A very small identical DNA segment, typically under 5–7 cM.

A map showing the location and frequency of genetic crossover points on chromosomes.

The combined visualization of your mapped segments across Chromosomes 1–22.

Tracing lineages backward using physical records, registries, and oral histories without DNA.

The Swedish term for systematic archival research, emphasizing source evaluation and criticism.

The formal record of where a specific historical or genealogical fact was found.

Historical church records documenting baptisms, marriages, burials, and local movements.

Official decennial government counts of populations, documenting households and occupations.

State-maintained records of births, marriages, and deaths (BMD), independent of church records.

The official document or register entry recording a child's birth date, location, and parents.

The official register entry recording a legal union between two individuals, often listing parents.

The official register entry documenting an individual's death, location, age, and sometimes parents.

Births, Marriages, and Deaths; the three core vital events of family tree research.

Legal documents relating to the distribution of a deceased person's estate, listing heirs.

Legal documents recording the transfer of land ownership between individuals.

Government rolls documenting service, enlistment, pension applications, and physical descriptions.

A running diary of research tasks executed, sources checked, and specific search results.

A running log of all messages sent to and received from DNA matches or archives.

A record created at or near the time of an event by a direct eyewitness.

A record or publication created later, compiling or analyzing primary source data.

Evidence that directly answers a genealogical question (e.g., a birth record naming parents) on its own.

Circumstantial evidence requiring correlation with other facts to build a proof case.

The absence of expected evidence, indicating that a certain event did not occur.

The established guidelines used to measure the credibility of a family tree conclusion.

A proposed explanation or pedigree branch that requires testing with evidence.

A classic ancestral chart showing your direct line of ancestors working backward in time.

A pedigree chart showing all descendants of a specific historical ancestor working forward in time.

The universal standard file format (.ged) used to transfer family tree data between software.

A person from whom you are descended (e.g., parents, grandparents, great-grandparents).

A person descending from a specific ancestor (e.g., children, grandchildren, cousin matches).

The average interval of time between the birth of parents and the birth of their offspring.

The specific time gap between generations, which can vary widely in different branches.

A collaborative DNA project grouping testers who share a specific surname, usually using Y-DNA.

A comprehensive research project documenting every instance of a specific surname worldwide.

A stubborn point in your family tree where the paper trail vanishes completely.

A targeted combination of DNA segment analysis and archival searching to resolve tree blocks.

The application of genealogical research standards to legal, biological, and parentage cases.

A case where a biological mother, father, or grandparent is completely undocumented.

A physical DNA kit that sequences your autosomes to identify cousin matches and ethnicity estimates.

A specialized DNA test that analyzes the Y-chromosome, passed exclusively from father to son.

A specialized DNA test that analyzes mitochondrial DNA, inherited strictly along the maternal line.

A statistical breakdown of your ancestral percentages across geographical reference regions.

A dataset of modern individuals with documented, deep regional ancestry used for comparison.

Highly specific ancestral groups identified through identical segment networks.

The text file listing your sequenced genotypes at each scanned base-pair position.

Genealogical Data Communication; the universal file format for digital family trees.

A testing platform that does not allow users to upload raw DNA files from other companies.

The act of importing your raw DNA data file into a compatible third-party database.

The act of exporting your raw genetic file from your testing company's settings.

A major branch of the human genetic family tree sharing a common ancestor with a specific mutation.

A more specific, downstream branch within a major genetic haplogroup.

The most recent, downstream mutation that defines your specific Y-DNA haplogroup branch.

The world's largest commercial DNA database with over 25 million testers.

The leading commercial DNA and genealogy platform for European and international matching.

The pioneer genetic genealogy lab hosting major Y-DNA and mtDNA lineage databases.

A commercial DNA service focusing heavily on genetic health risks and precise admixture.

A UK-based DNA company offering highly detailed breakdowns of British and regional ancestry.

A third-party database, free at its core with optional paid tools, that lets users compare segment files from different testing platforms.

An award-winning web app created by Jonny Perl for chromosome mapping and probability modeling.

A specialized software platform offering automated clustering and match monitoring.

An automated network analysis tool that clusters DNA matches into distinct color-coded grids.

An advanced probability tree tool hosted at DNA Painter.

A next-generation pedigree modeling tool built to handle complex trees.

A match sorting strategy using color-coded spreadsheets to group matches from 90–400 cM.

A cheek swab used to collect epithelial cells for DNA extraction.

Collecting DNA by spitting into a tube, used by AncestryDNA and 23andMe.

An analysis scanning specific, target DNA positions (SNPs) across the genome.

Reading the entire sequence of nucleotides along a strand of DNA without skipping.

High-throughput DNA sequencing technologies that can sequence entire genomes quickly.

The elite Y-DNA test from FTDNA, sequencing 700 STR markers and millions of SNPs.

A database tool tracing the geographical movements of haplogroups over time.

The dashboard panel where you control who can view your DNA matches and profile data.

Choosing to actively participate in research programs or law enforcement database sharing.

Choosing to exclude your DNA data from matching databases or scientific studies.

Allowing law enforcement agencies to compare cold-case crime scene DNA with genealogy databases.

The right to control your own genomic data and decide who can access or view it.

The strict European data privacy law regulating how corporate platforms handle your personal data.

Health Insurance Portability and Accountability Act; protects sensitive medical data in the US.

programmatic tools used to pull or compile data fields from family tree files.

A map displaying where specific downstream mutations developed historically.

Chromosomal regions where crossover events occur with significantly higher frequency.

A severe reduction in genetic diversity due to historical plague, famine, or migration.

Having tens of thousands of distant matches (under 10 cM), typical of endogamous cohorts.

Paying for specific cousins to test to prove or disprove a hypothesized tree branch.

The physical overlapping DNA segment shared by a verified triangulated group.

A grid matrix comparing matching segment coordinates across Chromosomes 1–22.

A Monte Carlo genetic simulation model used to verify relationship probabilities in BanyanDNA.

The pedigree tree structure and shared cM values analyzed within What Are the Odds.

The physical Excel log sheet used to execute the Leeds Method match grouping.

A probability model predicting the frequency of random events occurring in a fixed interval.

A spreadsheet recording where recombination breaks occur across your chromosomes.

An interactive utility painting ethnic or ancestral blocks across chromosome displays.

A matrix matching shared cousins against each other to identify clustering patterns.

The technical header and source tags compiled inside a standard GEDCOM file.

Downloading raw data from one company and uploading it to another compatible platform.

The estimated number of generations or years back to the shared ancestor of two matches.

The age differences between parent and child generations in a pedigree tree.

Grouping and analyzing DNA matches who share a common geographic or historical cohort.