Glossary of 20 key terms

The words that come up again and again, each defined in one plain line with an everyday example. Every term has its own link - search any single term and land directly here.

DNA Gene Genome Chromosome Variant SNP Allele Protein Mutation Inheritance Dominant Recessive Carrier Epigenetics Heritability Polygenic Polygenic risk score Genotype Phenotype Microarray

DNAThe absolute basics: The molecule that stores your genetic instructions, written in four letters: A, T, G, C.; e.g. The 'paper and ink' your whole genetic recipe book is printed on.
GeneThe absolute basics: A section of DNA that carries instructions for one specific job, usually making a protein.; e.g. One recipe in the book.
GenomeThe absolute basics: Your complete set of DNA — all your genes and everything in between.; e.g. The entire recipe book, cover to cover.
ChromosomeThe absolute basics: A package that stores your DNA; humans have 23 pairs.; e.g. The chapters the recipes are bound into.
VariantHow inheritance works: A small difference in a gene's spelling between people.; e.g. Why you handle coffee differently from a friend.
SNPGenetic testing 101: A one-letter difference in DNA at a single position; the most common kind of variant.; e.g. Pronounced 'snip'; the dots a DNA test reads.
AlleleHow inheritance works: One of the alternative versions of a gene you can carry.; e.g. Brown-eye version vs blue-eye version.
ProteinThe absolute basics: The molecule genes instruct your cells to build; proteins do the body's work.; e.g. The dish the recipe produces.
MutationThe absolute basics: A change in DNA; can be inherited or newly arising, harmful, harmless, or helpful.; e.g. A typo in a recipe — usually trivial, occasionally important.
InheritanceHow inheritance works: How genetic information passes from parents to children.; e.g. Why you have your mother's eyes.
DominantHow inheritance works: A variant that shows its effect even if you carry only one copy.; e.g. One copy is enough to see the trait.
RecessiveHow inheritance works: A variant that shows its effect only if you carry two copies.; e.g. Needs a copy from each parent to appear.
CarrierHow inheritance works: Someone with one copy of a recessive variant who is usually healthy themselves.; e.g. Can pass it on without having the condition.
EpigeneticsTraits & health: Changes in which genes are switched on or off, without changing the DNA itself.; e.g. The dimmer switches on your genes.
HeritabilityTraits & health: How much of the variation in a trait across people is explained by genes.; e.g. Height is roughly 80% heritable.
PolygenicTraits & health: A trait or risk shaped by many genes together, each with a small effect.; e.g. Height and most common diseases.
Polygenic risk scoreGenetic testing 101: A number summing many small genetic effects to estimate your risk for a condition.; e.g. 'Above or below average', not a diagnosis.
GenotypeThe absolute basics: The specific set of variants you actually carry.; e.g. Your version of the recipe book.
PhenotypeTraits & health: The observable result — your traits, how the genes actually show up.; e.g. How the dish turns out on the plate.
MicroarrayGenetic testing 101: A chip that reads hundreds of thousands of DNA spots at once.; e.g. The standard tool behind most consumer tests.