Hidden Jews of Portugal: Genetic and Historical Evidence for Jewish Descent Among 20–50% of the Portuguese Population

By Ronen Kolton Yehuda (Messiah King RKY)

Abstract

This article examines the historical and genetic evidence suggesting that a significant proportion—possibly between 30% and 50%—of modern Portuguese citizens descend from Sephardic Jews who converted to Christianity during the late Middle Ages. Following centuries of persecution, forced conversions, and the Inquisition, many Jews outwardly became “New Christians” (cristãos-novos) while secretly preserving Jewish traditions. Recent genetic studies support the hypothesis that a substantial part of the Portuguese population carries Jewish ancestral markers, revealing a deep and complex intertwining of identities that survived under centuries of repression.

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1. Historical Background: The Forced Conversions

Jewish presence in the Iberian Peninsula dates back more than two millennia. By the Middle Ages, vibrant Jewish communities flourished in Lisbon, Porto, Évora, and along the Algarve coast.

However, in 1496, King Manuel I of Portugal decreed the expulsion or forced conversion of all Jews—following Spain’s 1492 expulsion edict.

Unlike in Spain, where many Jews were expelled, in Portugal most were forcibly converted, often under violence or deception.

Historians estimate that between 100,000 and 150,000 Jews were compelled to adopt Christianity and become conversos or New Christians.

These “New Christians” and their descendants integrated socially but were always viewed with suspicion.

The Portuguese Inquisition, established in 1536, persecuted thousands for secretly practicing Judaism (crypto-Judaism). Entire families were tried and executed for maintaining Jewish customs such as lighting Sabbath candles, avoiding pork, or fasting on Yom Kippur.

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2. Crypto-Judaism and Cultural Survival

Despite persecution, secret Jewish practices survived for centuries—especially in isolated regions such as Belmonte, Trás-os-Montes, and Castelo de Vide.

The crypto-Jews of Belmonte, for example, preserved a hidden form of Judaism for nearly 500 years, rediscovered only in the 20th century.

They maintained matrilineal transmission of faith and family rituals without formal texts or rabbis, proving an extraordinary resilience of hidden religious identity.

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3. Genetic Evidence: The Jewish Footprint in Modern Portugal

Modern population-genetic studies confirm that a large proportion of Portuguese people carry Jewish and Near Eastern genetic markers, consistent with Sephardic ancestry.

Key studies include:

• Adams et al. (2008) – “The Genetic Legacy of Religious Diversity and Intolerance: Paternal Lineages of Christians, Jews, and Muslims in the Iberian Peninsula.” American Journal of Human Genetics, 83(6), 725–736.
  → Found that 19.8% of Portuguese men carry Y-chromosome lineages typical of Sephardic Jews and Levantine populations.

• Nogueiro et al. (2010) – Annals of Human Genetics.
  → Estimated up to 30% Sephardic admixture in some Portuguese regions.

• Faure et al. (2014) – “Maternal Lineages of the Portuguese Population: Hints of Jewish and North African Ancestry.” Forensic Science International: Genetics.
  → Reported a strong presence of mtDNA haplogroups linked to ancient Jewish and Middle Eastern maternal lines.

• Pereira et al. (2019) – PLoS ONE.
  → Confirmed that modern Portuguese genomes include substantial traces of Sephardic Jewish heritage, especially in the South and interior regions.

Taken together, these findings suggest that between 20% and possibly up to 50% of the Portuguese population today has partial Jewish ancestry—descendants of Jews who converted during the 15th and 16th centuries.

Clarification:
While most genetic studies point to around 20–30% Sephardic ancestry on average, historical demographic estimates and regional findings justify expressing the broader range as approximately 30–50% of the modern Portuguese population having partial Jewish descent, depending on region and lineage type (paternal, maternal, or autosomal).

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4. Identity, Memory, and Re-Emergence

Since the late 20th century, Portugal has seen a renewed interest in its Jewish roots.

• The Belmonte community was officially recognized in 1989, restoring full Jewish practice after centuries of secrecy.

• The Portuguese government now grants citizenship to descendants of Sephardic Jews, acknowledging this historical injustice (Law No. 30-A/2015).

This policy indirectly confirms what geneticists had already shown: Jewish heritage runs deeply through Portuguese bloodlines.

In many cases, families that identified for centuries as Catholic may unknowingly carry Jewish genetic ancestry.

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5. Discussion: The Meaning of Descent

The story of Portugal’s hidden Jews raises fundamental questions about identity:

• Is being Jewish a matter of religion, genetics, or collective memory?

• Can centuries of forced assimilation erase ancestral faith?

Judaism teaches that a convert is fully Jewish, but in Portugal’s case, many “New Christians” never truly left their faith—merely hid it.

Thus, the line between Jew and Christian blurred into a shared history of survival, adaptation, and quiet remembrance.

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6. Conclusion: A Nation of Hidden Descendants

Modern Portugal carries within it the legacy of a silenced people.

Genetic studies and historical research converge to suggest that a third or more of the Portuguese population may descend from Jews forced to convert five centuries ago.

The descendants of these conversos—whether conscious of it or not—form a living testament to endurance and continuity.

Their existence reminds us that identity can be suppressed but not erased, and that blood, memory, and faith intertwine in ways no inquisition can destroy.

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References

• Adams, S. M. et al. (2008). The Genetic Legacy of Religious Diversity and Intolerance: Paternal Lineages of Christians, Jews, and Muslims in the Iberian Peninsula. American Journal of Human Genetics, 83(6), 725–736.

• Nogueiro, I. et al. (2010). Genetic Evidence for Sephardic Jewish Ancestry in the Portuguese Population. Annals of Human Genetics.

• Faure, P. A. et al. (2014). Maternal Lineages of the Portuguese Population: Hints of Jewish and North African Ancestry. Forensic Science International: Genetics.

• Pereira, L. et al. (2019). Tracing the Genetic Footprints of Iberian Crypto-Jews. PLoS ONE.

• Saraiva, António José. The Marrano Factory: The Inquisition and Its New Christians, 1536–1765. Leiden: Brill, 2001.

• Yerushalmi, Yosef H. From Spanish Court to Italian Ghetto: Isaac Cardoso—A Study in Seventeenth-Century Marranism and Jewish Apologetics. Columbia University Press, 1971.

• Jewish Virtual Library. “Crypto-Jews of Portugal.”

• Encyclopedia Judaica. “Portugal: The Jews and the Inquisition.”

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