Britain and Ireland SNP and Surname Mapper
SNP or Surname Selection

Nothing to see here until you type or choose a SNP to view.

Select a county :     ★ indicates a county with 17th century church or hearth tax data

Visualizing History and Language in Surnames
notes ↓

Click any of the surname categories in the list to map such surnames by county. Below the map are references and a list of all of the surnames of this type; those in light gray are not present in the 1881 British and Griffith's Valuation Irish census data.

Because the intent of this tool is to show the pattern for multiple surnames, both the total prevalence by county and the number of matching surnames found in that county contribute to the color intensity.

Click the green button at the top of the list to enter your own surnames or haplogroups. For sets of surnames, use '*' as a wildcard.

Click the Map and Details tabs to see more information about individual names and counties.

Large haplogroups that long precede migration to Britain (e.g. R1b, I2a, E-M35) may show a Welsh bias due to the unusual distribution of Welsh surnames, not preferential settlement.

weighting: peoplesurnames         contrast: lowhigh

How to use this tool

In the Map tab, type in a SNP or surname and press the Enter key or the Go button. Use the Options choices to see more detail.
Select from the Examples menu or click for a random SNP. Option-click for a random surname.


This tool may give you hints about where and when your paternal ancestors lived but it cannot be definitive because it relies on probabilities, incomplete data, and often fine differences. To reduce visual clutter the map may show just one path, but always review the table(s) under the Details tab and draw your own conclusions about the likelihood of one county or one SNP versus another.

Treat SNP and path locations as hints and possibilities but not genealogical fact. A quality control study of nearly 500 users who have entered precise ancestral coordinates suggests that the average error in SNP location is about 160 km; see Sometimes the oddities of statistics imply wild paths through Wales or the Shetlands (see below), and remember that while your surname may have been most prevalent in one county, a specific ancestor could always have lived somewhere else.

Limited Early Data
The 19th century census data (1853-1865 Irish and 1881 British) are quite complete for every county, but the early data (1550-1650 church records in Scotland, 1664-1674 hearth tax records for England and Northern Ireland) are sparse, with no coverage for southern Ireland or Wales, and only six counties in England. Use wildcards to find variations -- for example MacDonald is absent but Donald and Donaldson are present in the early data.
Input and Display Options
Combining Y SNP data with comprehensive census data can be powerful -- and confusing. The table below highlights to indicate what the map shows, according to your choices.
Type of InputOptions ChoiceDetail LevelResulting Display
one SNPShow ancestorslow Paternal ancestry path shown as green line ending at labeled SNP origin; ancestor SNPs color-coded by epoch.
medium As above, with branch arrows showing paths of other descendant lines from common ancestors, and dashed circles showing location uncertainty.
high Alternative input SNP locations shown as pie charts showing surnames used to estimate location and size proportionate to total surname prevalence.
Show descendantslow Heatmap shows general location of descendant SNPs.
medium All descendant SNPs shown as triangles, color-coded by epoch.
high As above plus paths from input SNP to descendant SNPs.
multiple SNPsShow ancestorslow Same as above but paths color-coded by SNP
medium As above, color-coded by SNP.
high Alternative input SNP locations shown as pie charts with slice sizes proportionate to total surname prevalence.
Show descendantslow Heatmap shows general location of all descendant SNPs.
medium All descendant SNPs shown as triangles, color-coded by parent SNP.
high As above plus paths to descendant SNPs.
one surnamelow Heatmap showing general surname prevalence, by percent in county or total as selected.
medium Surname prevalence proportionate to county dot areas. Dashed circle encloses 80% of total prevalence.
high Possible SNPs associated with this surname shown with ancestral path; also see Details tab for SNP names, dates, data, and link to full tree.
multiple surnames, or one surname with wildcard spellinglow Heatmap showing total surname prevalence, by percent in county or total as selected.
medium County pie charts with area proportionate to prevalence and segments color-coded by surname.
high As above, SNPs deduced from multiple surnames.
The choice of prevalence by percent in county or by total applies to all surname displays.
Names here are geographic and not political, thus 'British Isles' refers to Great Britain, Ireland, the Isle of Man, Hebrides, Orkneys, Shetlands, and Channel Islands. Ireland is used here as the name of the island, not the country, especially since the surname-by-county data used here, Griffith's Valuation of 1825-1865, was completed before the political partition of 1921.
Many thanks to Maurice Gleeson and Keith MacGregor for continuous ideas, patience, and feedback. This project began with Keith's invitation and manual efforts to match up Y DNA with Scottish clan history for a conference. Early experiments showed that the scope could be far broader, and given the very high Anglo-Scots-Irish participation at FTDNA, and when Covid19 canceled the conference, there was suddenly time and reason to build the tool. Thanks also to Shane Wilson for Irish census data, Tom Patterson for the Natural Earth background map, FTDNA for making the Y haplotree accessible, and all of the crowd at David Langton's England-EIJ FTDNA project for early feedback about the maps and methods.

The methods here are different from those used in SNP Tracker. In SNP Tracker, older SNPs are located by the archaeological literature and post-Bronze Age SNPs are generally located as weighted averages of user-entered national origins. In this tool, again a handful of older SNPs are hand-placed based on historic evidence, but the majority of locations are based on matches between surnames in the Y haplotree and surnames in census data. See details at

Single Surnames: The most common situation is a search with a single surname, or with a SNP associated with a single surname which is increasingly common as BigY identifies recent terminal SNPs originating long after surnames arose in the 11th-13th centuries. The census data is searched for just that name: in fortunate cases the name is rare and uniquely located, like Keig, Cretney, or Kermode from the Isle of Man, and it's easy to suggest a possible ancestral location. But if the name was widespread, like Smith or Taylor, there is really no sure way to say where this lineage arose, even though one country will have always the highest prevalence.

Multiple Surnames with Common Y Ancestry: A SNP's place of origin can be much better estimated when there are two or more surnames associated with it, either by known history or by surnames added to the Y tree. This is well illustrated by several clan-related SNPs that spawn their own websites and societies; click these examples and look at the surnames in the Details tab: R-L226 (Ua Briain), R-M222 (Uí Néill), R-L1335 (Alpin), I-L126 (Isles), R-CTS2187 (Little Scottish).

This power of coincidence can also be used to find which SNP(s) may attach to two or more surnames. Because of the sparseness of DNA testing and the high likelihood of lineage extinction, most SNPs originating around 3000 years ago are still single-surname . Examples where two or three surnames define a SNP and its location are Morrison and McCown, Skaggs and Keig, Newman and Potter, Frame, Hamilton, and Scruggs, O'Leary and Cotter, Black,McFarlane, Hughes,McDaniel,Duffy. The Morrison-McCown case is written up in detail here

Boundary Identification: SNP Tracker relies on user-entered national origins for its post-Bronze Age locations. These data are too coarse-grained for location to the county level, but they can be used to estimate the SNPs that come immediately before and after a given Y lineage's migration to the British Isles, or when an R-L21 descendant line crossed from England into Scotland or Ireland. The pruning and bias that this offers greatly simplifies and improves the results of the census-based methods above. Details and examples are written up here .

Questions and Answers
  • Why didn't my SNP get an ancestral path line? SNPs that originated outside of Britain and Ireland have no ancestors on the map. Click Show Descendants to see if your SNP has viewable descendants. Also assure that your profile (accessed at FTDNA > Account Settings > Genealogy > Surnames) must include your paternal surname; in fact two or more matching surnames must be present for any given SNP for FTDNA to include that name in the tree.
  • Can you add or correct my SNP? My paper trail shows exactly where it should be. Yes, see below for personalization.
  • Why aren't mitochondrial SNPs mapped? Mapping here depends on a non-random correspondence between DNA surname data and surnames in the 19th century census data, and was no such relationship for maternal DNA in these societies.
  • Why is my path so convoluted? That could be the truth -- but also this occurs for common names which are very difficult to locate accurately. Always check the error circles shown for ancestors and medium detail -- you can probably ignore any extra twists and turns if these overlap along your path.
  • Why just Britain and Ireland? How about the US, Canada, Europe, etc. No other part of the world has the necessary data density, both in Y DNA testing and in accessible county-level census by surname, as Britain and Ireland (Finland might be an exception). The US, Canada, and Australia are too recently populated by Europeans and too mixed to have regionally specific surnames in the SNP timescale. For example the surnames Jenkins, O'Brien, and Ross have very strong regional roots in south Wales, southern Ireland, and the Highlands, respectively, but in the "colonies" they could be anywhere.
  • Why do my ancestors show up off-track in Wales or the Shetlands? These places are very different from everywhere else, with small populations and an even smaller number of surnames, which makes the percents of some names very high. Such names -- especially Jones, Smith, Williams, and Johnson -- have a very high prevalence in Wales or the Shetlands. This natural bias may suggest Welsh or Shetlands ancestry where there is none: check the details and make your own assessment.

Thanks to BigY DNA testing the Y SNP tree has grown to the point where many terminal SNPs now overlap the timescale of paper genealogy; this means that some men are able to pinpoint their SNP origins within one or two generations. I can add a precise location for you if the following conditions are met:

  • You have a SNP of known location in Britain or Ireland and formation date after 1600.
  • This SNP does not conflict with any other surnames or families unknown to you.
  • In your FTDNA profile, you have entered your paternal surname at Account Settings > Genealogy > Surnames.
  • Your email includes the SNP name, your paternal surname, the SNP formation date, and SNP origin latitude and longitude in decimal degrees, not degrees/minutes/seconds.
  • You agree that anyone else may view this information.
Ask for Custom SNP Location

Caveats, questions, comments, requests

This tool is entirely free and it comes with no guarantees. I have tried to make the maps fair and accurate but there will always be gaps and biases in the data. Results can change as new DNA data arrives, especially if users enter ancestal surnames where there were none before.

Please tell me about your ideas for improvement and stories where this tool has been of particular interest to you.

Rob Spencer    
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