The scientific argument for marrying outside your caste

Community-based marriage systems remain prevalent in India despite rapid urbanisation and the proliferation of smaller families.

Representational image of marriage | Photo: Pixabay

Bengaluru: As India becomes more globalised, there are intense deliberations in orthodox families on the merits of getting married within their own community.

The obvious go-to-market strategy is to ask for family recommendations and visit websites tailored for the community. This is typically followed by patrika and gotra matching, and some family meetings.

But as our scientific understanding of diseases and other heritable attributes increases, we have to question whether continued insistence on community-based marriages is relevant.

Endogamy is the practice of marrying within the same community, and genetic diseases arising out of a limited gene pool are a major consequence of it.

There is a growing need to reflect on these practices and determine what’s the best way to choose a life partner.

A tradition gains ground

Getting married within one’s community made sense through history, in times of longer commutes between villages and lack of effective communication tools.

Further, our social structures have dictated community behaviours for a long time, from the way communities prepare food to the way they pray (if they choose to).

It makes sense that parents prefer to get their children married within communities — it is easier to welcome a family member or send them into familiar traditions.

For example, a non-vegetarian woman marrying into an orthodox vegetarian family would find her diet constrained. Attending family gatherings if you do not speak your partner’s native tongue can also make you feel like an outsider.

But as India’s families become more nuclear, and globalisation transcends traditions, one has to wonder if it makes sense to stick to this community-based marriage system.

Endogamy today

Community-based marriage systems remain prevalent despite rapid urbanisation and the proliferation of smaller families. They are surprisingly more prevalent among rich urban Indians than the rest of the country.

The option of choosing from the community is really not wrong or unethical, but it comes today with one major caveat — genetic diseases.

Centuries of endogamy have lead to a limited gene pool within communities. If there is a defective gene in this gene pool, its presence gets amplified across generations. This might not necessarily lead to diseases.

Inbreeding led the Habsburg royals to have peculiar jaws and also eventually led to the demise of their rule as the last king could not produce any children.

The presence of genetic mutations that lead to diseases present in a community gene pool puts future generations at heightened risk. Striking examples of such phenomena are present all around the world, from the Ashkenazi Jews predisposed to Tay-Sachs to Arya Vaisya community members who cannot break down a particular anaesthetic molecule.

Interestingly, it is advised that one should not get married into one’s own gotra. This system suggests some semblance of cognisance that marrying into one’s family could cause adverse reactions. Yet, once a woman gets married, her gotra supposedly changes to her husband’s.

Under this system, one is allowed to marry their aunt’s children. The changing of gotra does not mean that the woman’s genes have changed, and you share an equitable gene pool across all your cousins. The custom of marrying cousins further exacerbates the impact of a decadent gene pool.

The freedom to make an informed choice

Community-based marriages should, therefore, come with a warning (actually this is true for any marriage, but endogamy increases the risk). The children of such a marriage may be predisposed to genetic defects and diseases.

For a select list of diseases, genetic tests are available to identify the likelihood of a potential child suffering from them.

For example, mutations that cause thalassemia, a blood disorder, are well-known. When both the genes in a child are mutated, the child suffers from a full-blown form of the disease — thalassemia major. If only one gene is mutated, the child suffers from a milder version — thalassemia minor.

Pre-checking of parental DNA for thalassemia-related mutations can predict the likelihood of the child developing thalassemia. If there is a strong likelihood, parents could choose to screen the child during pregnancy or opt for pre-implantation genetic diagnosis to determine and implant a healthy child.

Gene-testing is now becoming more common, with the idea of a gene “patrika” — to see whether a couple is genetically compatible — gathering ground.

However, robust scientific data only helps determine risk with regard to a limited number of diseases. There is no scientific evidence to perform genetic matches to pre-determine other attributes such as health, intelligence, etc. Genetic analysis is also not advanced enough to actually suggest matches based on compatibility. The danger with genetic testing, however, is that we have only scratched the surface of how genes work and what we can learn from studying them.

The other end of the genetic compatibility spectrum is to get swayed by untested scientific claims regarding marital compatibility and physical attributes of future children.

India as a society needs our future generations to be healthy, educated and productive individuals. There is a nature and nurture component to their development — endowing them with healthy genes, bringing them up in a peaceful environment, and providing them the opportunities to learn and explore.

But for that we need to give our current generations the education and freedom to make informed choices about their partners.

Shambhavi Naik is a research fellow with the technology and policy programme at the Bengaluru-based thinktank Takshashila Institution