DNA Glossary: Key DNA Definitions to Know [2024 Update]

Don’t feel bad if you don’t understand all the terms you see when shopping around for a DNA test kit. Some of the info can get pretty technical, and not everyone has a degree in genetics. To make things a bit easier, we’ve assembled a glossary of some of the most important DNA-testing terminology.

A

Aboriginal: Aboriginal relates to the original, native group from a particular geographic region. Allele: An allele is a genetic variant at a particular spot in your genetic code. American Indian: This is a term for the descendants from the earliest settlers of the Americas. Ancestral Haplotype: The ancestral haplotype is the group of alleles shared by descendants of a common ancestor. Ancestry: Your ancestry is your family or ethnic descent. Ashkenazi: This is the portion of the Jewish population that is descended from Central and Eastern Europe. Autosomal DNA: Autosomal DNA (atDNA) is DNA that is inherited from the autosomal chromosomes. This does not include the sex chromosomes. It’s the DNA that’s inherited from both of your parents.

B

Base: Bases are the chemical points where the information in DNA is stored as a “code.” There are four such bases: adenine (A), guanine (G), cytosine (C), and thymine (T). Human DNA has approximately three billion bases, more than 99% of which are analogous in all humans. Base Pair: A base pair is two complementary nucleotides on opposite strands of your DNA. Biogeographical Analysis: Biogeographical analysis is the examination of genetic changes over many generations within a specific geographic region.

C

Carrier: A carrier is someone who’s inherited a recessive allele for a genetic trait (disease). A carrier normally doesn’t outwardly show any signs of having the condition. Carrier Screening: This is a type of genetic test that can tell you whether or not you “carry” a gene for a particular genetic condition, which could be passed on to your children. Cell: A cell is the most basic and smallest unit of all life. Chromosome: A chromosome is a linear strand of genetic material wrapped around proteins. Humans have 23 pairs of chromosomes, including sex chromosomes (XX for females, and XY for males). Complex Trait: This is a trait whose inheritance cannot be explained by the genetic segregation of a single gene. It usually comes from multiple genes (and/or environmental factors) and exhibits a variety of observable characteristics.

D

DNA: Deoxyribonucleic acid (DNA), is the self-replicating material that is the primary component of your chromosomes. It is the unchanging carrier of your genetic information. DNA Profile: Also called a “DNA fingerprint.” Your DNA profile is the totality of all the values of a group of genetic markers that are identified in the analysis of your DNA. DNA Sequence: This is the result of the process used to determine the order of nucleotides in your DNA. This can be used to identify a person or diagnose genetic disorders. Dominant Trait: As opposed to being “recessive,” a genetic trait is one that will be outwardly demonstrated regardless of whether there is only one copy of the gene. Double Helix: A double helix is the twisted, rotating latter shape your DNA has as its two strands bond together.

E

Ethnicity: A group of people that share a common national or cultural background, often as a result of descending from the same area.

G

Genealogy: A line of descent traced continuously from an ancestor; or the study of family history. Gene: A gene is a segment of DNA that’s passed down over generations. Genetic: Genetic cousins are people that meet the criteria for being genetic matches in DNA testing. In other words, they’re related genetically. Genetic Drift: This is a change of gene frequencies (e.g., the presence of certain genetic traits) within a given population over time as a result of chance. Genome: A genome is the entire set of genes and genetic material you have in your cells. Genotype: A genotype is the part of your genetic makeup that determines a single trait or group of traits.

H

Haplogroup: Haplogroups are major ancestral branches on both your mother’s side and your father’s side of the family. They correlate with early human migrations and specific geographic regions. Haplotype: A short term for haploid genotype. It’s a tight group of genes that are passed down from one of your parents. Haploid: Haploid is a term describing a cell with a single set of chromosomes.

I

Inheritance: This refers to all the traits, conditions, etc. that have been passed down biologically from all ancestors, from our parents to our most ancient progenitors.

M

Markers: A marker is a gene or sequence of DNA with a physical location on a chromosome that can be used to identify individuals or species. Mapping: These are the methods used to describe the positions of genes that determine characteristics or conditions. Matches: Matches exist when the DNA test results of two people indicate a strong likelihood that they share a common genetic ancestor. Migration Patterns: These are the historically identifiable, geographic movements of particular groups, often seasonal or in search of resources. Mitochondria: Mitochondria are structures within your cells that are responsible for energy production. Mizrachi: Mizrahi is the portion of the Jewish population that is descended from Jews who historically lived in the Middle East, North Africa, and the Caucasus regions. Sometimes this group includes Sephardi Jews. mtDNA: Mitochondrial DNA (mtDNA) is a genetic material in mitochondria. It’s passed down only from mothers to both male and female children.

N

Neanderthal: This is an extinct human species that once inhabited areas of Europe during the Ice Age (approximately between 120,000 and 35,000 years ago). Notable physical features of the species include prominent brow ridges and a receding forehead. Nucleotide: A nucleotide is a structural piece of your genetic code. Each nucleotide is made up of one base plus a phosphate molecule and a sugar molecule. Nutrigenomics: This is a field of scientific study that is focused on the relationship between genetics, nutrition, and health.

P

Polymorphism: A genetic variation that results in the occurrence of several different forms or types of individuals among the members of a particular group.

R

Recessive Trait: As opposed to being “dominant,” a recessive genetic trait is only observed when two copies of that particular gene are present, meaning that it was contributed by both parents.

S

Sephardic: Jews who are of Spanish, Portuguese, or North African descent. Single nucleotide polymorphisms (SNPs): The naturally occurring and most common type of variation in DNA. Each SNP represents a difference in nucleotide.

T

Telomere: This is a portion of DNA at the tip of the chromosome. It protects the end of the chromosome from deteriorating or fusing with other chromosomes. Trait: A trait is an observable characteristic of your genes.

V

Variant: A variant is a microscopic difference in DNA that makes a person’s genome unique.

X

X Chromosome: The X chromosome is one of two sex chromosomes (the other being the Y chromosome). It’s the chromosome that’s present in both sexes. A male inherits one X chromosome from his mother, and a female inherits one X chromosome from her mother and one from her father.

Y

Y Chromosome: The Y chromosome is one of two sex chromosomes (the other being the X chromosome). It’s passed down exclusively from father to son. Y-DNA: Y-DNA is the DNA observable when examining a male’s Y chromosome. It is passed down from father to son.