Prohibition of Marriage Within the Same Surname and Clan: The History of Law Banning Love

How did the centuries-old law banning marriage within the same surname and clan begin and eventually disappear?

• Why the royal families of Silla and Goryeo used consanguineous marriage for political purposes
• The background behind the unprecedented ‘prohibition of marriage within the same surname and clan’ system in the Joseon Dynasty
• The process by which this law conflicted with individual freedom in modern society and was ultimately abolished

What if the law blocks you from marrying the one you love? It may sound absurd, but just a few decades ago in South Korea, tens of thousands of couples suffered because of the rule called Dongseongdongbon (same surname, same clan). This article follows the long and arduous journey of the Korean Peninsula’s marriage system, entangled with blood, power, love, and taboos.

A Tool for Royal Authority: Consanguineous Marriage in Silla and Goryeo

For nearly a thousand years on the Korean Peninsula, marriage between close relatives was not taboo but a core strategy to maintain power. Why did the royal families of Silla and Goryeo marry nieces, cousins, and even half-siblings?

Silla’s Sacred Bone: An Extreme Choice to Preserve Bloodline

Silla’s history began with a strict caste system called the Golpumje (Bone Rank System). As the name suggests, the purity of bloodline determined everything. At the top was the Sacred Bone (Seonggol), requiring both parents to be royalty.

This closed system was a ‘golden cage’ in itself. To maintain the Seonggol status, marriage had to occur only within the Seonggol, severely limiting choices. Ultimately, Silla’s royal consanguineous marriages were a practical and extreme solution to the contradictions created by their own system, beyond mere belief in sacred bloodlines.

• King Jinheung: Born from the marriage between his uncle (Ipjong Galmunwang) and his daughter (Jisobu-in). It was a marriage between uncle and niece.
• Kim Yushin and Kim Chun-chu: Kim Yushin married his sister Munhee to Kim Chun-chu, later marrying their daughter, becoming both brother-in-law and son-in-law to Kim Chun-chu.

Such extreme choices caused genetic vulnerabilities and succession confusion similar to the European Habsburgs, which some analyze as one cause of Silla’s downfall. A choice made to protect power ultimately became a shackle that tripped itself up.

Goryeo’s Clever Move: New Strategy to Control In-Laws

Founded in 918, Goryeo faced a different challenge. King Taejo Wang Geon had 29 wives to appease local nobles, which resulted in numerous in-law factions threatening royal authority.

At this point, the Goryeo royal family cleverly repurposed Silla’s ‘old strategy’ into a ’new trick.’ By encouraging consanguineous marriage within the royal family, they blocked external forces (nobles) from becoming the king’s in-laws and gaining power. This was a brilliant adaptation of an existing system to the political realities of the time.

King Gwangjong, the 4th ruler of Goryeo, formalized this strategy by marrying his half-sister, Queen Daemok Hwangbo. This was not mere imitation of Silla customs but a meticulous political and economic calculation to strengthen royal power and prevent royal property leakage.

A Great Shift: The Birth of the Prohibition of Marriage Within the Same Surname and Clan

The millennium-old custom faced a massive transformation at the end of Goryeo with the introduction of Neo-Confucianism. What was yesterday’s strategy became today’s sin.

Neo-Confucianism’s Sharp Edge Redefines Family

Neo-Confucianism emphasized strict patriarchal order and ritual propriety (‘ye’). To this new ideology, Goryeo royal consanguineous marriage was nothing but barbaric custom. The newly risen Joseon scholar-officials fiercely criticized it, arguing that marriage should conform to Neo-Confucian ethics (‘dori’), not royal power consolidation (‘pragmatism’).

King Sejong clearly expressed the changed spirit of the times, saying, “Could the reason the Wang family (Goryeo) ended after 500 years be due to consanguineous marriage?” The value of patrilineal blood purity fundamentally changed the definition of family.

A Law Unseen Elsewhere: Genealogy and Dongseongdongbon

Joseon adopted the Chinese 『Daemyeongryul』, banning marriage between people with the same surname (‘Dongseongbulhon’). But it went further by combining the uniquely Korean concept of ‘Bon-gwan’ (clan origin), creating the unique system of ‘prohibition of marriage within the same surname and clan’ (Dongseongdongbon geummon).

This was not just a legal reform but a massive social engineering project. The law became a powerful tool to absolutize the status of patrilineal clans. Since marriage required proof of surname, clan, and origin, genealogies (jokbo) spread explosively.

Interestingly, genealogies changed over time. Early Joseon recorded children in birth order regardless of gender, but from the 17th century, as patriarchy strengthened, they switched to the ‘sons first, daughters later’ method. Genealogies shifted from historical records to social weapons proving patrilineal purity.

Modern Clash: Love Topples the Dongseongdongbon Law

The centuries-old custom collided head-on with new values of individual freedom and happiness in the 20th century.

Tears of Couples Living Outside the Law

The Joseon custom of prohibiting marriage within the same surname and clan surprisingly continued as Article 809, Paragraph 1 of the South Korean Civil Code enacted in 1960. With industrialization and urbanization increasing encounters between same-surname clans, couples could not legally marry. Their children were stigmatized as ‘illegitimate’ and discriminated against in all social systems. I personally remember as a child vaguely wondering why adults said ‘people with the same Kim surname cannot marry.’

As the gap between law and reality widened, the government had to implement a temporary ‘special law’ allowing marriage registration for one year on three occasions starting in 1978. This was an implicit admission of the law’s contradictions by the state.

1997: The Day the Law Collapsed

Finally, in 1997, eight couples filed a constitutional review against Article 809, Paragraph 1, marking the climax of this history. The Constitutional Court became the stage where traditional values and individual freedom clashed.

• Supporters of retention (Confucian scholars): “Dongseongdongbon means one family. Repealing the law will destroy good morals and social ethics.”
• Supporters of abolition (women’s groups, affected parties): “It violates constitutionally guaranteed personal dignity, the right to pursue happiness, and freedom of marriage.”

On July 16, 1997, the Constitutional Court issued a ‘constitutional discordance’ ruling. The law was unconstitutional, but to avoid chaos from immediate repeal, it was given a grace period until the National Assembly revised it. This was a negotiated surrender of an outdated worldview and a historic decision that bought society time to forge a new consensus.

Conclusion

The marriage system of the Korean Peninsula has undergone a long and difficult journey intertwined with power, ideology, and individual lives. The key points of this lengthy drama are:

1. Marriage as Strategy: Consanguineous marriage in Silla and Goryeo was a clear political strategy to preserve bloodlines and control in-laws.
2. Marriage as Ideology: The Joseon prohibition of marriage within the same surname and clan was a unique social norm shaped by Neo-Confucian ideology, reinforcing patrilineal order.
3. Marriage as a Right: In modern times, marriage has been redefined from family tradition to a matter of individual freedom and the right to pursue happiness.

In 2005, the Dongseongdongbon prohibition was completely abolished and replaced with a reasonable standard banning marriage within the eighth degree of kinship. However, this story is not over. The current ‘within eighth degree’ rule faces criticism for being too broad by global standards, and new constitutional challenges are underway.

Family, tradition, and morality are never fixed. What do you think about the currently debated ‘within eighth degree’ prohibition?