Y-DNA Testing for Surname Research: Big Y-700 and Surname Projects

The reason Y-DNA testing exists at consumer scale is surname research. In most patrilineal naming cultures, a surname and a Y chromosome travel together down generations of fathers and sons. Two men who share both a surname and a closely matching Y-DNA result are almost certainly related through a paternal-line ancestor. Two men who share a surname but not a Y-DNA result are not related through that surname, and that absence of evidence is genuinely useful information for a genealogist working a brick wall.

Why Y-DNA is the right tool for this question

Autosomal DNA fades after five to seven generations because each generation halves the DNA inherited from any single ancestor. By a seventh-great-grandparent, most descendants will not show measurable shared autosomal DNA, even though they are biologically related.

The Y chromosome does not fade. It passes from father to son with only a small number of mutations accumulating per generation. Two men whose paternal lines diverged twenty generations back will still share a recognizable Y-DNA result, and matching focuses on which specific mutations they share or do not share to estimate when their paternal lines diverged.

For autosomal versus Y-DNA versus mtDNA, see autosomal vs Y-DNA vs mtDNA. For the broader concept of haplogroups, see what is a haplogroup.

Y-STR matching versus Y-SNP haplogroup placement

Y-DNA tests measure two different kinds of markers, and a surname-research test usually wants both.

Y-STRs, short tandem repeats, are positions on the Y chromosome that vary in the number of repeats between men. Y-STR results are reported as a set of numbers, one per tested marker. Two men whose Y-STR results match closely, with only a few differences across dozens of markers, share a recent common paternal-line ancestor. Y-STR matching is what powers the match list at FamilyTreeDNA’s Y-DNA service.

Y-SNPs are point mutations that, once they occur on a Y chromosome, are inherited by every descendant in that line. Y-SNPs define the phylogenetic tree of Y haplogroups. Placing a man’s Y on the haplogroup tree means identifying which Y-SNPs he carries and which he does not, and finding his position on the tree maintained by ISOGG.

A modern Y-DNA test reports both. Y-STR matching tells you who else in the database is a recent paternal-line relative. Y-SNP placement tells you where on the global tree your paternal line sits.

The Big Y-700 from FamilyTreeDNA

As of early 2026, the leading consumer Y-DNA test is FamilyTreeDNA’s Big Y-700. It is priced around $449 and frequently sold at a discount.

The product sequences roughly 700 Y-STRs and a large portion of the Y chromosome itself. The result is the most detailed Y haplogroup placement currently available to consumers, often resolving a person’s Y line down to a terminal SNP that defines a branch only a few hundred or a few thousand years old.

For most surname projects, the recommended starting test was historically Y-37 or Y-67, less detailed Y-STR-only tests. FamilyTreeDNA has shifted toward the Big Y-700 as its flagship product over the past few years, and most active surname projects now recommend customers test at Big Y-700 when their budget allows, with the smaller Y-STR tests as entry points.

FamilyTreeDNA is the only major consumer company that currently sells dedicated Y-DNA testing. 23andMe and Living DNA report a Y haplogroup as part of their autosomal kits, but they do not do Y-STR matching and they do not place the Y on the detailed branches of the tree the way a dedicated test does. AncestryDNA does not test Y-DNA at all.

Surname projects

A surname project is a group of men who share a surname or a variant spelling, organized at FamilyTreeDNA, who agree to compare Y-DNA results under the coordination of a volunteer project administrator. Membership is usually free; participants pay for their own tests.

ISOGG maintains a directory and a guide to surname projects, and FamilyTreeDNA itself lists active projects on its site. Long-established projects often have hundreds or thousands of participants and have used Y-DNA to identify multiple distinct genetic lines within a single surname, to settle long-standing debates about whether two families with the same name are related, and to push lineages back into the medieval period where documents fade.

Two examples of long-running, large-scale projects:

• The British Isles by County project, which clusters Y-DNA results by ancestral location across the British Isles and is one of the largest geographic-region projects.
• The Cumberland Gap and various large clan projects, including extensive Scottish and Irish clan studies, which use Y-DNA to identify the underlying genetic lineages of named clans.

Surname project administrators often guide new members on which test to order based on what the project most needs. If you are interested in a specific surname, search FamilyTreeDNA’s project directory before ordering and read the project’s recommendations.

What Y-DNA cannot do

Y-DNA does not tell you about your maternal line, your mother’s father’s line, or your father’s mother’s line. It is one strict line through your tree, the line of fathers. For a complete picture, autosomal DNA is the standard tool. Most genealogists use autosomal as the foundation and add Y-DNA or mtDNA when they have a specific lineage question.

Women cannot take a Y-DNA test directly because they do not carry a Y chromosome. A woman researching her paternal surname line needs a male paternal-line relative, a brother, father, paternal uncle, or paternal grandfather, to test on her behalf. This is one of the few clean limitations in consumer genetic genealogy and not an inconvenience the test design can engineer around.

For the broader pillar, see the ancestry and genealogy guide. For where Y-DNA fits among the test types, see autosomal vs Y-DNA vs mtDNA. For the haplogroup labels Y-DNA produces, see what is a haplogroup.