RE: Incest - pros and cons

Super interesting topic. I had a deep dive into how the ex-Soviet Muslim countries treat this. In ex-Soviet Christian countries, people consider cousin marriage a taboo (in families with Christian heritage). Georgians and East Slavs all think it's like marriage with a brother/sister - ugly and shameful. I never met such a couple in my life and never heard. In Muslim ex-Soviet countries, it happens.

Sharing some data.

Let's start with Kazakhstan:

Since ancient times, a rule known as 'Zheti Ata' operated on the steppe, prohibiting marriages between relatives up to the seventh generation. This helped preserve the purity of genes and prevent severe hereditary diseases in descendants. However, the recent surge in Islamization has called these laws into question. - source

Azerbaijan. From mass media, 49000 marriages yearly happen in Azerbaijan, and around 2000 marriages between relatives (between cousins or uncle + niece). Thus, it's 4% - much lower than in the Middle East. News:

The law banning marriages between close relatives came into force on July 1, 2025. According to the new regulations, marriages between the children of siblings who share a common grandfather or grandmother, as well as between biologically related cousins, are completely prohibited. Under the new law, all individuals applying for marriage are required to provide a birth certificate and documents about their parents to determine the degree of kinship. If violations are detected, administrative or criminal liability will apply... ..This measure, according to the lawmakers, will help protect children from serious illnesses. The number of sick newborns is increasing every year, as is the number of marriages between relatives. - source

Uzbekistan, 2024:

In Uzbekistan, authorities want to ban marriages between blood relatives along the collateral line, that is, between cousins. According to officials, such unions are a cause of congenital defects in children. One study claims that almost 10 percent of children with genetic disorders born in Uzbekistan last year were the result of consanguineous marriages - source

Kyrgyzstan:

there are many such marriages - from an article "Marriage with a cousin: allowed or fashionable?"

Tajikistan (non-Turkic), 2016:

From now on, in Tajikistan, it is forbidden for first cousins to marry, as well as for uncles and aunts to marry their nieces and nephews. It should be noted that the practice of marrying close relatives is widespread in Tajikistan, especially in the mountainous and rural areas of the republic. According to the country’s Ministry of Health, about 30–35% of children with disabilities are born to parents who are closely related, which is causing serious concern among the authorities. There are cases where four children in a single family have developmental disorders, and they were born to couples in close-kin marriages. Children who are deaf or blind are born to otherwise healthy parents. We conducted a nationwide survey, and the results revealed that the cause of the disabilities was precisely the factor of consanguineous marriages - source

Turkmenistan - ??