Additive Trait
Additive traits are controlled by multiple genes, with each gene contributing incrementally to the trait's expression. Examples include traits like height or skin pigmentation, where the combined effect of genes results in a trait that shows a wide range of variations in a population. This is different from dominant or recessive traits, where one gene has a more significant impact. 
Learn about DNA traits

Adenine
Adenine is one of the five bases found in nucleotides, the building blocks of nucleic acids like DNA and RNA. It is one of two purines (the other is guanine) and pairs with the base thymine in the DNA double helix. In RNA, it pairs with the base uracil.
Learn more about DNA nucleotides

Admixture
Admixture refers to the mixing of DNA from two or more distinct populations. It occurs when individuals from different ancestral groups reproduce, leading to a combination of their DNA in their offspring. Admixture can be observed by analyzing variations in DNA. Studying admixture helps scientists understand the interaction and migration of people throughout human history. 
Learn about unexpected origins results

Allele
An allele is a variant form of a gene or DNA marker found at a specific location on a chromosome. An individual inherits one allele from each parent, and these alleles can be the same (homozygous) or different (heterozygous). Alleles interact to determine a person’s characteristics and contribute to genetic diversity within populations.
Learn more about alleles

Amino Acids
Amino acids are fundamental building blocks of proteins—essential molecules in living organisms. They play crucial roles in various biological functions. Amino acids, coded by sequences of DNA, are linked together in a specific order to form proteins. Each of the 20 different amino acids has a unique chemical structure. The sequence of amino acids in a protein determines its shape and function, which ultimately affects an organism's traits and functions. 
Learn more about proteins

Autosomal DNA Testing
Autosomal DNA testing looks at the DNA in all of your chromosomes (except for your sex chromosomes) and then looks for large areas of shared DNA between you and other people in a DNA database to find close relatives.
Learn more about autosomal DNA testing

 

C

Centimorgans
A centimorgan (cM) is a unit that measures the amount of DNA between locations on a chromosome. Technically, the number for centimorgans between two genes indicates the likelihood of the genes being inherited together as a result of their proximity to each other. Centimorgans help geneticists map the positions of genes on chromosomes and understand patterns of inheritance. They are also often used as a unit of measure when describing the amount of DNA where two individuals match. 
Learn more about genetic inheritance

Chromosomes
Chromosomes are packets of DNA found in almost every living cell. All the chromosomes together have the genetic information necessary for creating and running a living organism. They’re necessary for cells to be able to make new copies of themselves.
Learn more about chromosomes

Codominance
Codominance is when two alleles of a gene for a trait are both fully represented. There is no blending (like for incomplete dominance) and neither allele is more dominant. Take, for example, your blood type. If you inherit one A allele and one B allele for blood type, you'll have both A and B blood types. 
Learn more about genotype

Cytosine
Cytosine is one of the bases found in nucleotides, which are the building blocks of nucleic acids like DNA and RNA. It is a pyrimidine and pairs with the base guanine in the double-stranded DNA molecule and in RNA.
Learn more about DNA nucleotides

 

D

DNA Code and Codons
The DNA code is like a language with only four “letters” and 64 three-letter “words” called codons. As unbelievable as it may seem, most of the diverse life on Earth is built from just these 64 codons.
Learn more about DNA code and codons

DNA Discovery
Who discovered DNA and when? No one person discovered DNA. Instead, many scientists uncovered more and more about DNA from 1869-1953, until it culminated in the discovery of the famous double helix.
Learn more about DNA’s discovery

DNA Double Helix
The DNA double helix is perhaps the most famous molecular structure in all of biology. It is made up of two long strands of DNA that are intertwined—like a twisted ladder—forming a three-dimensional spiral.
Learn more about the DNA double helix

DNA Function
The function of DNA is to store all of the genetic information that an organism needs to develop, function, and reproduce. Essentially, it’s the biological instruction manual found in most of your cells.
Learn more about DNA function

DNA Markers
DNA markers are specific regions or locations in DNA with variations that act as distinctive signposts in the genome. These markers help geneticists locate and identify genes associated with traits or genetic ancestry. By analyzing DNA markers, researchers can understand genetic diversity, trace lineages, and study patterns of inheritance. These markers serve as essential tools in genetic research, providing valuable insights into the relationships between genes and various characteristics.
Learn more about DNA markers

DNA Nucleotides
Nucleotides are the basic building blocks of nucleic acids, including DNA and RNA. In addition to forming DNA and RNA strands, nucleotides can play another important role: the role of an energy storage molecule.
Learn more about DNA nucleotides

DNA Replication
DNA replication is the process by which your cells create exact copies of their genetic code. When a cell divides, it must first make a copy of its own DNA to pass on to the new cell, which needs this DNA to function properly.
Learn more about DNA replication

DNA Sequencing
DNA sequencing is a technology for “reading” the individual components of the DNA double helix. DNA sequencing offers vast possibilities from learning about your genetic history to diagnostic and therapeutic applications.
Learn more about DNA sequencing

DNA Strands
You’ve probably seen the famous double helix of DNA—two strands of DNA intertwined like a spiral staircase. But do you know how that shape is formed? It starts with individual strands composed of nucleotide building blocks that are linked together in a row.
Learn more about DNA strands

DNA Structure
The structure of a DNA molecule is the famous double helix. This “spiral staircase” structure consists of nucleotides that are bonded to each other to form two long strands. The nucleotides of each strand pair with each other to form the staircase’s “steps.”
Learn more about DNA structure

DNA Sugar
The sugar in DNA, deoxyribose, is the “D” in DNA. If you look at a DNA double helix, it resembles a spiral staircase. The “rails” of the staircase—that is, the two strands of DNA—are known as the sugar-phosphate backbone.
Learn more about DNA sugar

Dominant Trait
A dominant trait is a characteristic that shows its effect when an individual possesses at least one copy of the dominant allele associated with it. This dominant allele's influence is strong enough to overshadow the presence of a recessive allele. People who are sensitive to bitter tastes, for example, have a trait that is largely determined by a dominant allele. 
Learn more about genotypes

 

E

Endogamy
Endogamy is the practice of people within a specific community or population having children with others in the same group over hundreds of generations. This can occur because of cultural or geographic factors. Common examples include Jewish populations in Europe and island populations in Southeast Asia. In genetic genealogy, a history of endogamy within a population can make it harder to distinguish between close and distant relatives. This is because individuals of the group have a higher likelihood of common ancestors and will share more DNA on average. Tools like Timber can make these relationships clearer.
Learn about Timber

 

G

Gene Variants
Genetic variants are differences in DNA sequences among individuals. These variations, sometimes called mutations, can involve changes in single DNA bases (called single nucleotide variants, or SNVs) or larger changes to entire genes or chromosomes. Genetic variants contribute to diversity within populations and can impact traits, susceptibility to diseases, and drug responses. Studying genetic variants helps researchers understand patterns of human history and health. 
Learn more about gene variants

Genes
While the terms “DNA” and “genes” are sometimes used interchangeably, they are not the same thing. A gene is a precise stretch of DNA that has the instructions for a particular protein that has a specific function in a cell.
Learn more about genes

Genetic Code
The genetic code is the “language” used by cells to translate the information in DNA into proteins. It consists of a set of rules that specify how sequences of three DNA "letters" (called codons) correspond to specific amino acids. The genetic code is universal, meaning it's nearly the same in all living organisms, and it's crucial for understanding how genes determine an organism's traits and functions. 
Learn more about the genetic code

Genetic Testing
Genetic testing is a scientific analysis of an individual's DNA to uncover information about their genes, chromosomes, and genetic variations. This process involves collecting a sample (e.g., blood or saliva), isolating DNA, and examining specific genes or regions. This testing can provide insights into a person's genetic connections to different populations and ethnic groups, helping them better understand their roots and heritage.
Learn more about DNA testing

Genome
A genome is the complete set of DNA that contains all of the instructions for building, maintaining, and running an organism. Every organism has a distinct genome. There is a human genome, a dog genome, a daisy genome, and so on.
Learn more about the genome

Genome-Wide Association Study
A genome-wide association study (GWAS) is a scientific approach that looks across a person's entire set of genes for connections between genetic differences and specific traits. It helps researchers find out which genetic changes might be linked to certain traits by comparing the genes of many people who have or don't have the trait.
Learn about polygenic risk scores

Genotype
Genotype refers to the specific set of genes that an individual carries. Differences in genotype can explain why one person might have red hair while another has blonde, why someone is more or less likely to be lactose intolerant, or why a person has bitter taste sensitivity.
Learn more about genotype

Guanine
Guanine, usually abbreviated as “G,” is one of the bases commonly found in nucleotides, which are the building blocks of nucleic acids like DNA and RNA. It is one of the two purines found in nucleic acids and pairs with cytosine in the DNA double helix and in RNA.
Learn more about guanine

 

H

Haplogroup
A haplogroup is a set of specific DNA markers inherited from a common ancestor. These markers are used to trace ancient human migrations and ancestry, offering insights into our distant genetic origins and historical population movements.
Learn about types of DNA testing

Heritability
Within a population, how much variation in a particular trait (phenotypic variance) can be explained by the variation in peoples’ genes (genetic variance). Heritability is measured as the ratio of genetic variance to phenotypic variance.
Learn more about heritability

 

I

Imputation
Imputation is a method that predicts missing genetic information for an individual based on patterns found in existing genetic data. It uses known variations in DNA to estimate unknown ones, helping researchers understand genetic traits and diseases. The imputation process aids in building complete genetic profiles for individuals and populations when some data may be missing. 
Learn more about imputation

Incomplete Dominance
Incomplete dominance is when two different alleles of a gene don't fully dominate each other. Instead, they are both partially represented, often mixing together to create a new, in-between trait. For example, if you cross a red flower with a white one, you might get pink flowers.
Learn more about DNA traits

 

M

Maurice Wilkins
It seems everyone knows about Watson and Crick and their role in discovering the DNA double helix. But a third man, Maurice Wilkins, was part of the trio awarded the 1962 Nobel Prize for this discovery.
Learn more about Maurice Wilkins

Mitochondrial DNA 
Mitochondrial DNA (mtDNA) is genetic material inside mitochondria, structures in cells. A person’s mitochondrial DNA is only inherited from their mother—unlike nuclear DNA, which is inherited from both parents. Mitochondrial DNA carries genes vital for the cell to produce energy. Because mtDNA changes slowly, it's useful for tracing maternal ancestry and studying human evolution. 
Learn about types of DNA testing

 

N

Non-coding DNA
Non-coding DNA (sometimes called “junk DNA”) doesn't contain instructions for making proteins. Instead, it regulates gene activity, affecting when and how genes are used. Non-coding DNA plays a crucial role in controlling gene expression and various cellular processes.
Learn more about non-coding DNA

Nucleic Acids
Nucleic acids store and transmit genetic information, existing as DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). DNA holds the genetic code, determining an organism's traits, while RNA assists in translating this code into proteins, essential for cellular functions. These molecules form the core of genetic information, crucial for understanding heredity and life processes.
Learn more about DNA nucleotides

 

P

Pedigree Collapse
Pedigree collapse is when a person's pedigree has fewer unique ancestors than expected, and therefore shrinks instead of growing in certain generations. It happens when a person's ancestors have children together over several generations, resulting in some ancestors appearing multiple times and fewer unique ancestors than expected. It impacts genetic genealogy because of the increased shared DNA among relatives, complicating the determination of exact relationships. Understanding pedigree collapse is crucial for accurate genealogy research and interpretation. Looking at patterns of shared DNA can make these relationships clearer.
Learn more about shared DNA

Phasing
Phasing refers to determining the specific combination of alleles  that an individual inherits from each biological parent. It helps create an organized picture of the genetic information, highlighting which alleles come from the mother and which from the father. Phasing is crucial for tracing your origins, traits, and matches across different lineages. Multiple methods have been developed for phasing DNA, including Ancestry’s SideView™ technology.
Learn more about DNA phasing

Phenotype
Phenotype is a description of your physical characteristics. It includes visible traits, like eye color and height, and behavioral traits, like aspects of your personality. Your genes plus your environment help determine your phenotype.
Learn more about phenotype

Polymerase
A polymerase is an enzyme that plays a vital role in DNA replication and RNA synthesis. It does this by assembling nucleotides into long chains. DNA polymerases replicate the genetic code, ensuring accurate copying. RNA polymerases transcribe DNA into messenger RNA (mRNA) for protein production. 
Learn more about DNA replication

Polygenic Risk Score
A polygenic risk score (PRS) is a calculated value that reflects the combined influence of multiple genetic variations on a particular trait or characteristic. It compiles data from various DNA markers to estimate an individual's genetic predisposition for that trait. These scores are valuable for predicting traits or features influenced by multiple genes.
Learn more about polygenic risk scores

Proteins
Proteins are an important class of molecules responsible for carrying out most of the work inside cells. The building blocks of proteins are smaller organic molecules called amino acids. Each gene has the instructions for making a specific protein that has a specific job to do in the cell.
Learn more about proteins

Purines
Purines are essential molecules in genetics, serving as building blocks for DNA and RNA. They include adenine (A) and guanine (G). These molecules play a fundamental role in storing and transmitting genetic information in all living organisms.
Learn more about DNA molecules

Pyrimidines
Pyrimidines are vital molecules in genetics, specifically in DNA and RNA. They encompass cytosine (C), thymine (T), and in RNA also uracil (U). These compounds are fundamental components of genetic material, responsible for encoding and transferring genetic instructions within all living organisms.
Learn more about DNA molecules

 

R

Recessive Traits
A recessive trait is one that only manifests when an individual inherits two identical recessive alleles for that trait, one from each parent. Recessive traits, like not being sensitive to bitter tastes, are masked by dominant alleles when present.
Learn more about genotype

Recombination
Recombination is the process where, during the formation of eggs or sperm in a parent, sections of DNA on pairs of chromosomes are exchanged and combined to create new combinations of genetic variants. Recombination leads to unique genetic combinations in offspring. This genetic shuffling increases genetic diversity and plays a crucial role in evolution.
Learn more about genetic inheritance

RNA
RNA is the less famous, single-stranded cousin of DNA. RNA plays a critical role in turning DNA instructions into proteins. It also may have been the key molecule when life began on Earth 3.8 billion or so years ago.
Learn more about RNA

Rosalind Franklin
Rosalind Franklin was a scientist whose work was instrumental in one of the greatest discoveries of modern science: the structure of DNA. Her work with DNA and her contribution to the discovery of the double helix were largely overlooked in her lifetime.
Learn more about Rosalind Franklin

 

T

Thymine
Thymine, usually abbreviated as “T,” is one of the bases commonly found in nucleotides, which are the building blocks of nucleic acids like DNA and RNA. It is a pyrimidine and pairs with adenine in double-stranded DNA. In RNA, thymine is replaced by uracil.
Learn more about thymine

Types of DNA Testing
There are multiple types of DNA tests. The three most common are Y-DNA testing, autosomal DNA testing, and mitochondrial DNA testing. All of these DNA tests can help you learn more about your genetic heritage.
Learn more about types of DNA testing

 

U

Uracil
Uracil is a nucleotide and one of the basic building blocks of the nucleic acid RNA. RNA carries the information from DNA to other parts of the cell.  It is critical to the functioning of a cell.  
Learn more about RNA
 

W

Watson and Crick
The names James Watson and Francis Crick are linked to the discovery of the DNA double helix. Although Watson and Crick did no experiments of their own, their synthesis of the work of others was key to figuring out the structure of DNA and earned them Nobel Prizes.
Learn more about Watson and Crick
 

X

X-DNA
X-DNA refers to the DNA found on the X chromosome, one of the two sex chromosomes. The other sex chromosome is the Y chromosome. Typically, most people get one X chromosome from their biological mother, and an X or a Y chromosome from their biological father. While much of the DNA on the X chromosome influences sex characteristics, the rest influences various other traits and functions in the body.
Learn more about X-DNA

 

Y

Y-DNA
Y-DNA refers to the DNA found on one of the sex chromosomes, the Y-chromosome. Most biological males have one Y chromosome and one X chromosome. Most biological females do not have Y chromosomes; they have two X chromosomes. 
Learn more about Y-DNA