A review of Sri Lanka's genetic inheritance challenge

The recent findings on consanguinity rates in Sri Lanka by Dr. Thurairajah's team, as reported in The Sunday Times, have brought a longstanding but often private practice into the public health discourse.

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With a national average of 7% and rates approaching 25% among Tamil communities, Sri Lanka presents a compelling case for a comparative global analysis. But how does Sri Lanka's experience fit into the global picture? What can we learn from nations that have confronted similar challenges, some successfully, others less so? This investigation takes Dr. Thurairajah's findings as a starting point for a broader exploration.

Sri Lanka stands at a crossroads. Will it learn from international successes and act proactively, or will it wait, as Britain did, until the problem demands belated, reactive intervention? The evidence from around the world suggests that the answer to this question will be measured not in policy documents, but in the health of children not yet born.

Consanguineous marriage, unions between blood relatives, is far more common, worldwide, than most people realise. According to research published in Reproductive Health, approximately 10.4% of the global population lives in consanguineous unions, affecting over 1.1 billion people. The practice is not confined to any single region, religion, or economic status.

The highest rates appear in North Africa, the Middle East, and West Asia, where consanguinity rates can exceed 50% in some communities. Pakistan reports rates between 50-60%, while several Middle Eastern countries show similar figures. Even in Europe, immigrant communities from high-consanguinity regions maintain the practice at significant levels. Bradford, England, for instance, has documented that 37% of Pakistani-origin marriages are between first cousins.

Sri Lanka's 7% national average actually places it on the lower end of the global spectrum, though the 25% rate among Tamil communities aligns more closely with patterns seen in South India, where cousin marriage has deep cultural roots, stretching back centuries.