If you have Central or Western European ancestry, you have probably struggled to get meaningful results from generic G25 calculators that blur together populations which are actually historically quite distinct. The Central-Western Europe Calculator by Oliver, available on ExploreYourDNA, was built specifically to address this problem. By anchoring its source populations to carefully chosen ancient DNA references, spanning Bell Beaker, Germanic Iron Age, Hallstatt Celtic, and Roman-era samples, it offers a level of historical resolution that general-purpose tools cannot match.

1. The Historical Layers of Central-Western Europe

Central and Western Europe is genetically one of the most layered regions on earth. The modern populations of France, Germany, the Netherlands, Belgium, and neighbouring countries descend from at least four major ancestral episodes that have left distinguishable, if overlapping, genetic signatures in present-day genomes.

The deepest of these is the Bell Beaker substrate. Between 2500 and 1800 BCE, groups carrying the Bell Beaker package, characterized by a distinctive material culture and high proportions of Steppe-related ancestry, swept across Northwestern Europe. Their descendants formed the ancestral population of both later Celtic-speaking and Germanic-speaking peoples. In the Netherlands and northern France, this founding signal is captured particularly well by the ancient individuals from Valkenburg in the Dutch coastal zone, who represent a pre-linguistic, broadly Bell Beaker Northwestern European ancestral component.

By the Iron Age (circa 800, 50 BCE), a recognizable Germanic cultural and genetic block had emerged in Jutland and the North Sea littoral, distinguishable from the Bell Beaker base by the increasing contribution of Scandinavian Hunter-Gatherer ancestry via the Nordic Bronze Age. Meanwhile, the Hallstatt Celtic world crystallized in central Europe, present-day Austria, Bavaria, and the Rhineland, and later the La Tène expansion spread Celtic culture from the Alps into France, Britain, and Iberia. Finally, Roman military and civilian migration during the first four centuries CE introduced a measurable Southern European, Mediterranean-inflected ancestry into the Rhine-Danube frontier zones and Roman urban centres.

2. The Calculator Sources: What Each Proxy Represents

The strength of any G25 calculator lies in the choice of its source populations. Oliver's Central-Western Europe Calculator is built around seven ancient DNA reference groups, each carefully selected to represent a distinct historical ancestry layer. Here is what each source captures and why it was chosen.

3. Bell Beaker vs. Germanic: The Calculator's Core Strength

The most important axis this calculator resolves, and the one that general-purpose G25 tools handle most poorly, is the distinction between the original Bell Beaker Northwestern European substrate and the later Germanic Iron Age signal. This separation matters because it allows us to see which parts of a modern individual's genome reflect the pre-linguistic founding population of Northwestern Europe, and which reflect the specifically Germanic character that emerged in Jutland and the North Sea coast during the Bronze and Iron Age.

The key contrast in G25 space between Netherlands_Valkenburg_IA (Bell Beaker proxy) and Denmark_Jutland_IA (Germanic proxy) is subtle but consistent. The Jutland Iron Age individuals carry a higher loading on the PC dimensions that capture Scandinavian Hunter-Gatherer ancestry, the signature of the pre-Indo-European inhabitants of Scandinavia whose ancestry was incorporated into the Germanic gene pool during the Nordic Bronze Age. Valkenburg individuals, being from the Dutch coastal zone, lack this elevated Scandinavian component.

This ordering corrects a common intuition: although the Netherlands is geographically close to the Valkenburg source sites, modern Dutch populations, especially Dutch North, score notably more Germanic (Jutland_IA) than Brittany does, because centuries of Frankish, Saxon, and Frisian settlement added a real Germanic ancestry layer on top of the coastal Bell Beaker substrate. Brittany, by contrast, was barely touched by the Frankish expansion that reshaped the Low Countries, and retains the highest Valkenburg_IA signal of any modern population in the dataset. Populations from Schleswig-Holstein and Mecklenburg-Vorpommern, geographically closest to the Jutland source, naturally anchor the Germanic pole.

4. Hallstatt and Roman Ancestry: Separating the Celtic and Mediterranean Layers

Beyond the Bell Beaker/Germanic axis, the calculator's second major strength lies in its ability to distinguish Hallstatt Celtic ancestry from Roman-era Mediterranean admixture, two historically real signals that generic calculators frequently conflate, since both pull individuals slightly southward in standard G25 space.

The Hallstatt Signal

The Hallstatt culture (circa 800, 450 BCE) originated in the eastern Alpine zone and spread Celtic language and culture across a vast arc from the Iberian Peninsula to Anatolia. Genetically, Hallstatt individuals carry a somewhat elevated EEF (Early European Farmer) component compared to purely Bell Beaker Northwestern Europeans, reflecting the deeper south-central European substrate they inherited. This signal becomes important for southern German regions (Bayern, Baden-Württemberg), eastern France (Alsace), and the Rhine-Moselle zone where Hallstatt Celtic culture was most concentrated.

In the calculator, both Germany_Hallstatt_IronAge and France_SouthEast_IA2 capture this component from slightly different angles. The German Hallstatt samples represent the culture's Alpine heartland; the southern French Iron Age samples represent the Gaulish reception of Hallstatt and La Tène Celtic culture in the Rhone corridor, which was also the main gateway for early Greek and Etruscan Mediterranean contact before Roman conquest.

The Roman Signal

Roman conquest brought not just roads and aqueducts but people. The Italy_Imperial source captures the genetically cosmopolitan profile of Roman-era Italy, which already differed from modern Italians by carrying higher Near Eastern ancestry than the modern Italian average, reflecting the Empire's demographic mobility. The Austria_MigrationPeriod_Pannonian source adds a related but distinct late Roman-frontier component. Together, these two sources model the Mediterranean-shifted ancestry that Romans, legionary veterans, traders, and slaves introduced along the Rhine-Danube limes and into provincial urban centres.

5. PCA: All Populations in G25 Space

The chart below projects all 43 modern populations and 7 ancient reference samples from this calculator onto their first two principal components, derived from a PCA run on the complete set of G25 scaled coordinates. PC1 (60% of variance) is the dominant axis: it separates the Germanic-Scandinavian pole (right, anchored by Denmark_Jutland_IA) from the Southern European and Hallstatt pole (left, anchored by Italy_Imperial). PC2 (13%) separates Atlantic/Celtic populations (top) from Eastern European populations carrying Slavic drift (bottom, anchored by Poland_Early_Medieval_Slavic).

French regions are split into three groups to highlight a distinction that matters for this calculator: northern Atlantic France (Brittany, Lower Normandy, Pays de la Loire) plots visibly further right and upward than Germanic-influenced northern France (Upper Normandy, Picardy, Nord-Pas-de-Calais, Champagne-Ardenne, Alsace, Lorraine), the latter cluster sitting clearly between the Belgian positions and core French territory, reflecting their partial Germanic overlay from Frankish settlement and their geographic proximity to the Low Countries.

Dutch German Belgian France, Atlantic (Brittany / Lower-Normandy / Pays-de-Loire) France, Germanic-influenced North & East France, Interior & South Ancient reference

Figure 4: PCA of all 43 modern populations and 7 ancient references included in this calculator. Computed from G25 scaled coordinates. PC1 (60% variance) runs from Germanic/Bell Beaker (right) to Southern European (left). PC2 (13%) separates Atlantic/Celtic (top) from Slavic-drifted eastern populations (bottom). Hover over any point to see its name.

Several patterns stand out clearly. Dutch North plots almost as far right as the ancient Valkenburg_IA reference, confirming its strong Bell Beaker / proto-Germanic substrate. Brittany, despite being geographically in France, positions clearly to the right and above the Germanic-influenced French group (Upper Normandy, Picardy, Alsace), reflecting its preservation of Atlantic Bell Beaker ancestry with minimal Frankish admixture. The Germanic-influenced northeastern French regions (Alsace, Lorraine, Champagne-Ardenne) cluster between Belgian and core French interior positions, consistent with their documented Frankish and Alemannic settlement history. Finally, Corsica is the most extreme outlier in the entire dataset, sitting far left on PC1 and below the main French cluster, close to Italy_Imperial, a direct confirmation of its Mediterranean, non-Bell Beaker genetic character.

6. Patterns Across Central-Western European Populations

The G25 coordinate data available for the populations in this calculator reveal several coherent geographic and historical patterns worth understanding before you run your own results.

Table 1: Expected dominant and secondary source contributions for key Central-Western European populations, based on their G25 coordinates and historical background. Note that these are interpretive expectations; individual results may vary.

7. How to Use the Calculator

Using the Central-Western Europe Calculator is straightforward if you already have your G25 coordinates. Here is a step-by-step guide.

1. Obtain your G25 coordinates. If you have tested with 23andMe, AncestryDNA, or MyHeritage, you can generate G25 coordinates using the tools available on the ExploreYourDNA Calculators page. You need your scaled G25 coordinates (not the unscaled version).
2. Open the calculator. Navigate to the Central-Western Europe Calculator by Oliver. The calculator interface runs on Vahaduo, which will open in a linked tab.
3. Paste your coordinates into the "target" field. Format: YourName,PC1,PC2,...,PC25. Click "Run" (single mode for one individual, multi mode for several).
4. Interpret your results. You will receive a percentage breakdown across the seven source populations listed above. Focus primarily on the Bell Beaker (Valkenburg), Germanic (Jutland IA), and Hallstatt (Hallstatt IA + France SouthEast IA2) signals. Roman (Italy Imperial + Austria Migration Period) will only be significant for populations with genuine Roman-era ancestry.
5. Compare against the reference populations below. The G25 coordinates of modern Central-Western European populations provided in Section 7 below can be used as benchmarks: paste them as additional targets to see how your results compare to regional averages.

8. G25 Coordinates: Central-Western European Reference Populations

Below are the G25 scaled coordinates for a comprehensive set of Dutch, Belgian, German, and French regional populations. These can be used as reference targets in the calculator to compare your own results against population averages, or loaded into Vahaduo for multi-target runs.