There is a "Knanaya Christian Community" in Kerala which considers itself genetically pure. To maintain the purity, the siblings are forced to get married to each other in this community. A Kerala Court has banned it now. Kottayam Court said that it is not a matter relating to religion.

Members of the Knanaya community consider themselves to be descendants of Jews-Christians who migrated to Kerala from Mesopotamia. As per the church, they uphold endogamy, or the practice of marrying from within the same community, to continue the community's “pure lineage”. The Community has about 1,67,500 members in Kottayam and nearby areas. There are about 218 Priests and nuns in the community. 

The practice followed by the Knanaya Catholic Church of the Archeparchy of Kottayam was termed a violation of the fundamental right to marry (under Article 21) and the right to religion (under Article 24) as written in the Indian Constitution, was ruled by the Additional Sub Court of Kottayam.

The Knanaya Catholic Church upholds the practice of endogamy, and followers have been known to be ousted from the community if they marry outside of it, even followers of other Catholic Christian churches. This was challenged by Knanaya Catholic Naveekarana Samithy, who is a group of reformists, along with people who have faced similar expulsion. The petitioners had, in their plea, asked to stop the practice of ousting Knanaya followers for marrying people belonging to other Catholic Churches. Members of the Knanaya community consider themselves to be descendants of Jews who migrated to Kerala.

Sudheesh Kumar S, Additional Sub Judge of Kottayam, restrained the Metropolitan Archbishop of the Archeparchy of Kottayam and the Major Archbishop of the Syro Malabar Major Archiepiscopal Church (under which the former belongs), from terminating the membership of any member of the Archeparchy of Kottayam for marrying a Catholic from any other Diocese. The court also ordered the church to readmit all those who were expelled by the church, their spouses, and children, “if they qualify other respects on receipt of proper application”.

The spiritually orphaned members are even being denied the right to burial in the tombs where their parents and forefathers are laid to rest. Children adopted by couples are denied membership in the Parish,” the petitioners reportedly stated. The church also denies membership to children of Knanaya families who are born through surrogacy.

It was also added in the petition that hundreds of youngsters following the Knanaya faith remain unmarried due to the fear of expulsion from the church. 

Assessing various arguments and evidence submitted by petitioners and the church, the court ruled that the practice of endogamy cannot be termed a ‘custom’, and also said that Knanaya Catholic is not a separate religious denomination.

The court also added that the practice of compulsive endogamy “is in violation of the right to marry enshrined in Article 21 (Protection of life and personal liberty) of the Indian Constitution, which can simultaneously be recognized as a common law right and a fundamental right.” The forfeiture of membership for violating endogamy is a violation of the right guaranteed under Article 25 (freedom of conscience and free profession, practice, and propagation of religion) of the Indian Constitution, court added.