Genetic Genealogy Glossary and FAQ
Glossary
- Autosomal DNA — DNA on the 22 pairs of non-sex chromosomes, inherited from both parents.
- Centimorgan (cM) — a unit of genetic linkage used to measure shared DNA segments.
- Haplogroup — a group of people who share a common ancestor on the paternal or maternal line, defined by SNPs.
- mtDNA — mitochondrial DNA, inherited from the mother.
- SNP — a single-nucleotide polymorphism, a one-letter change in DNA.
- STR — a short tandem repeat, a short sequence repeated several times.
- Y-DNA — DNA on the Y chromosome, passed from father to son.
Frequently asked questions
Which test should I take first?
It depends on your question. For a surname or direct paternal line, Y-DNA; for a direct maternal line, mtDNA; for finding relatives on all your lines in recent generations, autosomal. See the science behind DNA tests.
Can a woman trace her father’s surname with DNA?
Not with her own Y-DNA, because she does not have a Y chromosome, but a brother, father, paternal uncle or male cousin on that line can test.
How accurate are ethnicity estimates?
They are estimates based on comparison with reference populations and can change as companies update their data. Treat them as a broad guide rather than evidence about a particular ancestor.
Is my DNA data private?
That depends on the company and the settings you choose. Read the terms and privacy policy before testing or uploading results, and see publishing DNA results responsibly.