Cousin Marriages in Islam: A Comparative Study of Religious Legitimacy and Genetic Implications in the Light of Contemporary Medical Research

Abstract

This paper examines the practice of cousin marriage from the perspective of Islamic teachings and medical sciences, and attempts to clarify religious governance, measure health risks, and propose a balanced and evidence-based pathway. The study is based on the high rate of intimate marriages in Muslim-majority societies which is more than 50% in Pakistan and many Arab countries and is based on the misconception that Islam specifically enforces or promotes such marriages. The first chapter establishes the framework of Islamic law: cousin marriage is absolutely permissible according to the Qur'an (4:22-24), the Prophet's marriage to his cousin Zaynab bint Jahsh, and scientific consensus. However, allowing consent is different from recommendation; cousin marriage falls into the category of neutral (favorable), encouraging (favorite). The Prophet's authoritative guidance and Caliph Umar ibn al-Khattab's saying "Weaken your children, therefore marry outside your tribe" clearly encourage out-of-state marriage for healthy children. The framework of the draft Shari'ah (protection of life, children, and intellect) and the principle of "no harm" (no harm, no harm) provide a strong Islamic justification for security measures. Chapter 2 examines the medical evidence: first-degree relatives share 6.25% of their genes (intermittent coefficient F=0.0625), which increases the risk of genetically prevalent diseases. Infant mortality increases by about 1.1%, major birth defects double from 3% to 6%, and certain conditions such as thalassemia β and visual impairment are significantly more common, especially when kinship is multiracial. A study of 110 visually impaired university students in Lahore found that all of them had relatives' parents, although most families were unaware of genetic linkages and mistakenly believed that Islam encouraged cousins to marry. Chapter III shows the synergy between Islam and medical science: Premarital screening programs in Saudi Arabia, Iran, and Kuwait significantly reduced the incidence of thalassemia without banning cousin marriages.