How is a gene test actually done?
You give a saliva or blood sample, a lab reads specific points in your DNA, and a report tells you what those points say.
Your sample contains cells, and cells contain your DNA. The lab extracts that DNA and reads it — either checking hundreds of thousands of specific spots (the common consumer approach) or reading whole genes in depth (the clinical approach).
The reading is then compared against research to produce your report. You give the sample once; the DNA itself does not change, so the raw data can be re-read as science advances.
Last reviewed 29 May 2026 · reviewed by someone with genetics training