The Allure of the Percentage
In the age of consumer DNA testing, millions of people have submitted saliva samples and received in return a percentage breakdown of their ancestry. For many people of Cape Verdean descent, these results have been revealing, confusing, surprising, or affirming — sometimes all at once.
A result might read: "West African: 52%, Iberian: 31%, North African: 12%, Other: 5%."
What does this mean? What doesn't it mean? And how should someone who identifies as Badiu — as culturally, historically, and emotionally rooted in Santiago Island — interpret this kind of data?
What Genetics Actually Measures
Population genetics measures patterns of inherited genetic variation — specifically, which stretches of DNA you share with reference populations. The percentage figures from consumer testing companies are statistical estimates, not precise measurements. They are calculated by comparing your DNA to reference panels made up of modern people who are assumed to represent specific ancestral groups.
There are several important caveats:
Reference panels are imperfect. The "West African" reference panel in most consumer tests draws heavily on a limited set of well-studied West African ethnic groups. Specific groups — Balanta, Serer, Papel, and others who were heavily represented in the Santiago slave trade — may be poorly represented or entirely absent from these panels.
Admixture happened over many generations. The Badiu are not recently mixed. They have been a distinct population for 15+ generations. The specific proportions of African, European, and North African ancestry were largely fixed centuries ago. What you see in a test today reflects that deep history, not any recent mixing.
Autosomal tests average across all ancestors. Your autosomal DNA represents all of your ancestors roughly equally. This means it cannot tell you which cultural practices you inherited, which language your ancestors spoke, or which community they belonged to. It tells you about population-level genetic patterns, not individual histories.
The Cape Verdean Genetic Landscape
Published academic studies — notably by Beleza et al. (2012) and Semedo et al. (2015) — have examined Cape Verdean genetics with more rigorous methodology than consumer tests.
Their findings consistently show:
Santiago Island has the highest Sub-Saharan African ancestry of any island in the archipelago — typically 50–70% in autosomal estimates, higher for mtDNA (maternal lineages). This reflects the island's history as the primary reception point for enslaved Africans, and the relative isolation of its interior communities from subsequent European immigration.
The Iberian component reflects enslaver ancestry. Y-chromosome studies show elevated European haplogroups compared to mtDNA studies, consistent with the historical pattern of European men fathering children with enslaved African women. This is not a neutral "mixing" — it reflects the power dynamics of slavery.
North African signatures are real but complex. A North African/Berber genetic component appears in most Cape Verdean studies. Its origins are debated: it may reflect Berber individuals brought to Cape Verde during the early slave trade (some North Africans were enslaved and transported), pre-Saharan population structures in West Africa, or early contacts through trans-Saharan trade networks.
What Genetics Cannot Tell You
Genetics cannot tell you whether you are Badiu.
Being Badiu is a cultural, linguistic, historical, and community-rooted identity. It is defined by the language you speak, the music you grew up with, the island your family comes from, the stories your grandparents told you — not by the proportion of your autosomal DNA that aligns with particular reference populations.
A person with 70% "European" autosomal ancestry who grew up speaking Kriolu in Tarrafal, whose family has been on Santiago Island for ten generations, is Badiu. A person with 100% "West African" autosomal ancestry who has no connection to Cape Verde is not.
This distinction matters enormously. Genetic nationalism — the idea that ancestry percentages define ethnic or cultural belonging — is scientifically incoherent and politically dangerous. The history of racism is, in part, a history of using biological markers to determine social membership. We should not replicate that logic, even when the intention is positive reclamation.
Genetics as Historical Evidence
Where genetics is genuinely valuable is as historical evidence — as a tool for understanding the population history of Santiago Island, the patterns of the slave trade, the demographic effects of colonization, and the connections between Cape Verdeans and specific African ethnic groups.
When studies show that Santiago's Y-chromosomal haplogroup E-M2 frequencies are especially close to those found among Mandinka and Serer populations, that is historically meaningful. It points toward the likely origins of many enslaved people brought to the island. It may help future researchers identify specific communities in West Africa with which Santiago families share deep connections.
This is the legitimate and powerful use of genetic data: not to determine who "belongs," but to trace the paths of people who were forcibly moved, whose records were deliberately destroyed or never kept, and whose histories have been systematically erased.
An Ethical Commitment
This project approaches genetic data with the following commitments:
All genetic claims are derived from peer-reviewed academic studies, not consumer testing company marketing materials.
All figures are presented as population-level estimates with explicit uncertainty ranges.
Genetic data is never used to adjudicate who is or is not Badiu.
The history of slavery — including the sexual violence embedded in European-African genetic admixture — is acknowledged directly, not sanitized.
Community knowledge, oral histories, and cultural identity are treated as equally valid sources alongside scientific data.
The Badiu are not a genetic category. They are a people with a history, a language, a music, a homeland, and a future.
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Key sources: Beleza, S. et al. (2012). Semedo, I. et al. (2015). See [Methodology](/methodology) for full citations.