Did Holy Prophet صلى الله عليه وسلم encourage or discourage marriages between cousins over several generations?

Question

What does Islam say about marrying your 1st cousins for several generations? Is it encouraged or discouraged?

Edit: There is a practice in some Asian countries that families tend to marry within themselves for many generations such that upto 3-4 generations have couples who were first cousins.

Science today tells us that marriages within the family over many generations contracts the gene pool and may lead to diseases and deformities.

I'm aware that Islam allows marriages between cousins. But does it allow encourage or discourage their children, grand children, great grand children and so on to again marry just their cousins?

Answer 1

Marriage with cousins is permissible, it has been explicitly permitted in 33:50.

Nothing authentic has been narrated from the Prophet ﷺ regarding whether it is encouraged or discouraged. Nor has anything been narrated regarding doing it over several generations.

Some scholars among the Shafi'is and Hanbalis have adopted the stance that it is preferable that the bride should not be among the close relatives (such as cousins) because there is a risk of divorce and hence may become a cause of severing ties of kinship (see المغني) and they also base it on the hadith (of doubtful authenticity):

لا تنكحوا القرابة القريبة فإن الولد يخلق ضاويا

Don't marry a near relative as in that case a child is born weak

^{— Ihya’ ‘Uloom al-Deen}

Others have denied this because the Prophet ﷺ himself married his cousin Zaynab bint Jahsh, and he married his daughter Zainab to her cousin Abu al-As ibn al-Rabi', and he married his daughter Fatimah to his own cousin Ali ibn Abi Talib.

Answer 2

I disagree with the post by hussain kazmi. Just because it is not prohibited, does not mean it is encouraged; it's simply permissible. I believe the Prophet did marry his cousin (Zaynab) but this does not mean we copy the same, because he married her for specific reasons.

Therefore, I do not believe there are any Islamic teachings that explicitly say that marrying your cousin is rewardable or encouraged. It is merely permissible; however, there are recent studies that show that consanguineous marriages are more likely to result in disabilities, so it would be unwise to do so while aware of that fact.

Answer 3

Of Course, Islam encouraged cousin marriage (or Islam preferred marriage within the family rather than out of the family). As Allah mentioned in Al-Nisaa 4:23:

Prohibited to you (for marriage) are: your mothers, daughters, sisters; father's sisters, mother's sisters; brother's daughters, sister's daughters; foster-mothers (who breastfed you), foster-sisters (who breastfed from the same woman as you); your wives' mothers; your step-daughters under your guardianship, born of your wives with whom you have consummated marriage, no prohibition if ye have not consummated; (those who have been) wives of your sons proceeding from your loins; and two sisters in wedlock at one and the same time, except for what is past; for Allah is Oft-Forgiving, Most Merciful.

It is very clear from above verses that Allah gave permission for Cousin Marriage.

Now regarding your main question, Prophet Muhammad encouraged cousin marriage.