Logo: © FamilyTreeDNA / Gene by Gene, Ltd. Used for editorial purposes. Source: familytreedna.com.
Of all the tools available to genealogists today, Y-DNA testing may be the most powerful for answering a specific and historically stubborn question: are these two men with the same surname actually related, and if so, how far back does their common ancestor sit? Y-DNA passes virtually unchanged from father to son, generation after generation, carrying the same genetic signature down a direct male line for centuries or even millennia. When combined with documentary research, it can confirm relationships, break through brick walls, and reveal connections that paper records alone could never establish.
This article focuses primarily on FamilyTreeDNA (FTDNA) — hereafter referred to as FTDNA — the only major consumer genetics company[1] that offers dedicated Y-DNA testing at multiple levels of resolution. We’ll cover what STRs and SNPs are, how the various testing levels differ, what the Big Y-700 provides that nothing else can, and how to make sense of the results. A brief callout covers what other testing companies offer for Y-DNA, which — compared to FTDNA — is limited.
Who Can Take a Y-DNA Test?
Only genetic males (those who have a Y chromosome) can take a Y-DNA test directly. Women do not inherit a Y chromosome. However, women researching their paternal line can ask a brother, father, paternal uncle, or male cousin on that line to test on their behalf. Because the Y chromosome passes only from father to son, any male in the direct paternal line — no matter how distant — carries the same Y-DNA signature.
This is both the strength and the limitation of Y-DNA: it traces one line exclusively. It tells you nothing about your mother’s father’s line, your father’s mother’s line, or any other branch. But for that one direct paternal line — the line that carries your surname through the generations — it is extraordinarily informative.
The Two Types of Y-DNA Markers: STRs and SNPs
To understand Y-DNA testing, you need to understand the difference between the two types of genetic markers being measured. They work differently, change at different rates, and answer different genealogical questions.
STRs: Short Tandem Repeats
An STR (Short Tandem Repeat) is a location on the Y chromosome where a short sequence of DNA letters repeats a variable number of times. At a given STR location — say, DYS393 — one man might have the sequence repeat 13 times, while another has it repeat 14 times. That difference is the “allele value” at that marker.
STRs mutate relatively quickly in genetic terms — roughly once every few hundred to a few thousand years at any given marker. This makes them useful for genealogical timeframes. Two men who share the same values at 37 or 67 STR markers are very likely related within a genealogically meaningful number of generations. The more markers tested, the more precisely you can estimate when their common ancestor lived.
When comparing two men’s STR results, the key measurement is genetic distance — the total number of markers where their values differ. A genetic distance of 0 at 37 markers means their Y-DNA is identical at all 37 locations tested. A genetic distance of 4 at 111 markers suggests a more distant relationship. FTDNA’s Time Predictor (TiP) tool uses genetic distance combined with known mutation rates for each marker to estimate the probability that two men share a common ancestor within a given number of generations.
SNPs: Single Nucleotide Polymorphisms
A SNP (Single Nucleotide Polymorphism, pronounced “snip”) is a single change at one specific position in the DNA — one letter changing from, say, a C to a T and staying that way permanently. Unlike STRs, SNPs almost never mutate back once they change. This means that every man who carries a particular SNP descended from the one man in whom that mutation first occurred — no matter how many thousands of years ago that was.
SNPs are the basis of the Y-DNA haplogroup system. When a SNP is found in multiple men and its position in the family tree is established, it gets a formal name (such as R-M269 or I-M253) and becomes a branch on the worldwide Y-DNA haplotree. Your haplogroup is defined by the most recent — most “downstream” — SNP that has been confirmed in your DNA.
Because SNPs change so slowly, they primarily tell you about ancient ancestry — where your paternal line was thousands of years ago. But the Big Y-700 test is changing this picture, identifying SNPs that are recent enough to be genealogically useful and creating an increasingly fine-grained map of lineage branching within the last few centuries.
FamilyTreeDNA’s Y-DNA Test Levels
FTDNA offers three main tiers of Y-DNA STR testing, plus the Big Y-700 as its premium sequencing option. Each higher level includes all the markers from the levels below it.
Y-37 — $119
The entry-level test, measuring 37 STR markers. Y-37 is a reasonable starting point for someone new to Y-DNA testing who wants to see whether there are close matches in the database. At 37 markers, matches within a genetic distance of 4 are considered potentially meaningful. However, the resolution at this level is limited — you may find many matches who are related only distantly, and distinguishing close relatives from distant ones can be difficult. Think of Y-37 as a first look, useful for identifying whether further investment is worthwhile.
Y-111 — $249
The most useful STR-only test for genealogical purposes, measuring 111 markers. At this level, the genetic distance thresholds become meaningful for genealogical work: matches within a genetic distance of 10 are displayed, and the closer the distance, the more likely a relationship within a documentable number of generations. Y-111 is particularly valuable for surname projects, where project administrators compare the results of multiple men sharing a surname to identify distinct family clusters. If you’re joining a surname DNA project, Y-111 is the level most administrators will recommend at minimum.
Big Y-700 — $449
FTDNA’s comprehensive Y-chromosome sequencing test — and the most powerful Y-DNA product available to genealogists. The Big Y-700 does everything the Y-111 does and much more:
- Tests all 111 STR markers used for standard matching
- Tests an additional 589+ STR markers (700+ total), not used for matching but available for lineage-specific analysis
- Scans the entire genealogically relevant Y chromosome for both known and novel SNPs — providing hundreds or thousands of SNP results
- Places you on the world’s most detailed Y-DNA haplotree with your most refined possible haplogroup assignment
- Identifies “private” SNPs — mutations unique to your line that may eventually become new branches on the haplotree as more men test
The Big Y-700 is a test that genuinely keeps giving over time. As more men test, private SNPs become shared SNPs, new branches form, and TMRCA estimates become more precise. Results from 2020 look different today than they did when first delivered, as the database has grown and the haplotree has been refined.
🌳 Haplogroups and the Y-DNA Tree of Humankind
The human Y-DNA haplogroup system organizes all of humanity’s paternal lineages into a single branching tree, rooted in Africa and branching outward as ancient populations migrated across the globe over tens of thousands of years. Major haplogroups are labeled with capital letters — A through T — representing the deepest branches. Each major haplogroup branches into subclades defined by specific SNPs, creating an ever-more-detailed tree of human paternal descent.
Common haplogroups in European-descended populations include R1b[2] (dominant in Western Europe, especially common in Britain, Ireland, and Germany), R1a (Eastern Europe and South Asia), I1 and I2 (Scandinavia and the Balkans), and E1b (parts of Europe with African ancestry). For DFA members with Dillman roots in Germany and Switzerland, haplogroups R1b and its subclades are the most common starting point, though individual lineages vary.
With an STR-only test, FTDNA assigns a predicted haplogroup based on your STR signature — an educated estimate that is usually correct at a broad level but may not identify your most precise subclade. Only the Big Y-700 definitively places you on the haplotree by directly identifying your SNPs. If knowing your precise haplogroup placement matters to your research, the Big Y-700 is the only test that delivers this with certainty.
Reading Your Big Y-700 Results: Key Tools
The Block Tree:[3] A visual representation of how you and your Big Y matches relate to each other, organized by shared SNP blocks. Men who share the same terminal SNP cluster together. The further back you go on the Block Tree, the more ancient the shared ancestor. The Block Tree is often the first place researchers look to identify which of their matches are most closely related.
The Time Tree (Discover): FTDNA’s Discover tool takes your confirmed haplogroup and places it on a time-scaled tree, estimating when each branch formed — when the most recent common ancestor of a haplogroup subclade was likely born. These Time to Most Recent Common Ancestor (TMRCA) estimates use a rate of approximately 83 years per SNP[4] as a baseline for Big Y-700 data. The Time Tree can tell you, for example, that the branch you share with a group of matches likely formed around 1600 CE — potentially placing a common ancestor within the surname period and within reach of documentary research.
Private Variants: SNPs found in your Big Y-700 results but not yet found in any other tester. These are mutations unique to your line as of the time of testing. As more men test — particularly others in your surname or geographic cluster — private variants become shared variants, forming new named branches and narrowing the TMRCA estimate. Recruiting related men to test is one of the most productive things a Big Y-700 tester can do.
FTDNATiP™: For STR-level matches, the TiP report calculates the probability that two men share a common ancestor within a given number of generations — 4, 8, 12, 16, 20, or 24 generations — based on their genetic distance and the mutation rates of the specific markers where they differ. It is a probabilistic tool, not a definitive answer, but it helps prioritize which matches deserve further documentary investigation.
Surname and Haplogroup Projects: FTDNA hosts thousands of free group projects[5] organized by surname, haplogroup, and geographic region. Project administrators — typically experienced volunteers — analyze results, organize members into family clusters, and help interpret findings. For researchers working on a specific surname, joining the relevant surname project is one of the highest-value steps available. Project administrators often have years of accumulated knowledge about which STR patterns indicate which family clusters.
The Dillman Family Association maintains a Y-DNA surname project at FamilyTreeDNA for men carrying the Dillman surname and its variant spellings. If you are a male Dillman researcher — or can arrange testing through a male relative on that line — joining the project connects your results with those of other tested Dillman men, allowing project administrators and fellow members to identify family clusters, confirm relationships, and extend research beyond what documentary records alone can reach. This is precisely the kind of coordinated effort where Y-DNA testing delivers its greatest genealogical value. Learn more about the DFA’s genetic genealogy efforts on the Dillman DNA Project page.
Practical Strategy: Which Test Should You Take?
For most Dillman Family Association (DFA) members beginning Y-DNA research on a Dillman line, the practical path is straightforward. Start with Y-37 if budget is a significant concern and you simply want to see whether matches exist. Move to Y-111 if you want to participate meaningfully in a surname project and get genealogically useful matching data. Consider the Big Y-700 if you are serious about breaking through brick walls, want your definitive haplogroup placement, or are working with others to build out a surname cluster using SNP data.
One important note: FTDNA stores your DNA sample, so you can upgrade from any lower level to a higher level at any time without retesting. Starting at Y-37 does not lock you in — you can add Y-111 or Big Y-700 later from your account dashboard.
What Other Companies Offer for Y-DNA
FamilyTreeDNA is the only major consumer genetics company that offers dedicated Y-DNA STR testing and the Big Y-700 sequencing test. Other companies touch Y-DNA only peripherally:
23andMe includes enough Y-chromosome SNPs on its autosomal chip to assign a broad haplogroup — typically to a major branch level. No STR testing, no matching, no detailed subclade placement. Useful as a starting point to confirm your major haplogroup, but not a substitute for dedicated Y-DNA testing.
Living DNA similarly provides a Y-DNA haplogroup assignment as part of its full ancestry kit, with somewhat better resolution than 23andMe in some haplogroups. Again, no STR matching, no Big Y-equivalent. Useful for haplogroup confirmation but limited for genealogical work.
AncestryDNA and MyHeritage — as of January 2026, both have removed Y-DNA and mtDNA data from their raw DNA downloads, making even haplogroup extraction from those files no longer possible for new tests.
YFull (yfull.com) is a third-party analysis service, not a testing company. If you have Big Y-700 Binary Alignment Map (BAM) file data from FTDNA, you can upload it to YFull for independent analysis and TMRCA estimates, which some researchers use to cross-check FTDNA’s results. YFull maintains its own Y-DNA tree and can provide additional perspective on haplogroup placement.
Full Genomes Corporation (FGC) offers deep Y-chromosome sequencing as an alternative to the Big Y-700 for researchers wanting maximum coverage, though at higher cost and with a more technically demanding results interface.
For practical genealogical Y-DNA work — matching, surname projects, haplogroup refinement, TMRCA estimation — FamilyTreeDNA remains the only game in town.
Getting Started
If you’re a male Dillman researcher — or if you have a male relative who carries a Dillman or variant surname — Y-DNA testing is one of the most targeted investments you can make in your genealogical research. The Dillman surname DNA project at FamilyTreeDNA, if one exists or is established, is the logical starting point: connecting with other tested Dillman men and comparing results is where the real research happens.
Explore Y-DNA testing at: familytreedna.com/products/y-dna
Y-DNA testing at FamilyTreeDNA: Y-37 ($119), Y-111 ($249), Big Y-700 ($449). Sale pricing is offered periodically. Only genetic males can test directly; women can arrange testing through a male relative on their paternal line. DNA samples are stored by FTDNA, allowing upgrades without retesting.
Sources
- FamilyTreeDNA, “Y-DNA Testing,” familytreedna.com/products/y-dna (accessed May 2026).
- ISOGG, “Haplogroup R1b,” isogg.org/tree/ISOGG_HapgrpR.html (accessed May 2026).
- FamilyTreeDNA, “Big Y-700 — Block Tree,” familytreedna.com (accessed May 2026).
- FamilyTreeDNA, “Big Y-700 — Discover Tool — TMRCA,” familytreedna.com (accessed May 2026).
- FamilyTreeDNA, “Projects,” familytreedna.com/projects.aspx (accessed May 2026).
AI Disclosure: This article was researched and written with the assistance of Claude, an AI assistant developed by Anthropic. All facts have been reviewed for accuracy, but readers are encouraged to verify information independently, particularly for time-sensitive details such as pricing and software versions.
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