Cousin marriages of the world, one of several charts in Wikipedia, covering the world, and USA states.
I married a second cousin, who is a statisticians, so I am interested in the statistics regarding first and second marriages and the health of the offspring of these marriages. We were aware, and worried about the dangers.
We just knew vaguely about the types of dangers. Having seen friends' lives constantly disrupted, and parents' health suffering, and siblings not getting attention, I am even more concerned.
I have now read that there are increased risks of babies dying at birth or under the age of five. Of being bed-bound for life. Of being non-verbal so they need supervision every moment of the day and whenever they go out. Of one parent having two or more handicapped children, having decided it was God's will, or fate, or random so that they might have been luckier next time, but were not luckier. Worse still, an addiitonal type or risk, babies in Nepal born with eye cancer.
Another risk is that the parent or step-parent might be exhausted or angry and torment an already suffering child. One can envisage a challenging child, who is crying, not talking, or apparently not co-operating, or just needed non-stop attention.
First Cousin Marriages
First cousin marriages are more dangerous, higher risk to offspring, than second cousin marriages. Siblings and parent child relationships, even riskier. Multiple generations of cousin marriages increase the risk.
We had one child and having had a successful outcome, did not take further risks by having more. That was back in the nineteen seventies when we did our own research. Now the internet and newspapers provide ready access to everybody.
Relative Risks Of Cousin Marriages
In Setpember 2025 I read a claim that fewer than 10% of children being affected by health problems meant that the majority of couples were not affected. I regard that as a misleading statement. Low risk is not no risk.
The low risk means cost of time, money, suffering of the handicapped, time needed lifelong from parents, and often forgotten siblings who have burdens of care and less attention and time from parents busy with attending to the handicapped, and services needed. This affects both the individual family, and the NHS and doctors, nurses, carers, grandparents, extended families, large families, insurance companies and treasurers, govenments, teachers and journalists.
When you look at the statistics of those affected, not just percentages, but numbers needing costly 24 hour lifelong care, from the point of view of The NHS, nurses, local dcctors, schools, and the national population, you are looking at a large number of people.
Even if you look at it from the point of view of any couple having a low risk, would you put your children in the queue of 100 children for a fairground ride if only 4-6 children would end up with a lifelong handicap?
Families Affected By Risk Increased By Cousin Marriages
Let's look at a long street, or small village, or doctor's patients, or a social worker or a nurse doing a weekly or daily visit. We are not necessarily talking about 100 families having one child. If every family has two children, 8-12 parents are affected. If every family has four children, 16-24 families are affected. If they have eight children, 32-48 families are affected.
One argument put forward in favour of allowing, or not preventing, or not warning against the risks, is that the risk is no greater than that of late births to older mother or older parents.
Many people are against older parents having children.
Firstly, many people choose to have children when younger to decrease that risk.
Secondly, you cannot stop yourself getting older, but you can choose to seek out a partner who is not closely related.
Thirdly, if you are at risk, you can limit your family size, to reduce the risk of burden to the parents, and the firstborn, and society.
Useful Websites
https://en.wikipedia.org/wiki/Cousin_marriage
