Marrying your cousin, is considered ideal and actively encouraged some cultures and communities, especially in the Indian subcontinent.
Cousin marriage generally, is also popular in Middle East, where it accounts for over half of all marriages in some countries.
In general there is no real medical or moral reason not to marry a cousin, but where its a first cousin marriage and the parents come from the same practise, then there are some issues to consider. For instance in India, where northern Indian Hindus treat all kinds of first cousin marriage as incest, but where Hindus in the south don't always take this view, and Muslims don't consider it any taboo .....
... then the practice of marrying your cousin, leads societies to what is termed high levels of consanguinity aka 'blood relationships' (which is the quality of being descended from the same ancestor as another person), in these communities, which is perhaps not healthy for population, or the individuals.
There is evidence that such marriages increase the risk of various genetic disorders in children with children of first-cousin marriages having an increased risk of genetic disorders, particularly if their parents both carry a harmful recessive mutation, while children of more distantly related cousins have less risk of genetic disorders. Research among Arab populations, and others worldwide has indicated that high degrees of consanguinity have an effect on some reproductive health parameters, such as postnatal mortality and rates of congenital malformations.
When the worldwide populations of homo-sapiens was small, such marriages or relationships must have been very common, indeed its been estimated that 80% of all the marriages in history may have been between second cousins or closer. However in the last few millennia, this has increasingly ceased to be the case, and the reason for such marriages is generally religious or cultural. For instance to preserve family wealth, strengthen family ties, or because its considered healthier. In the West, proportions of first-cousin marriage have declined since the 19th century, as social mobility allowed for a greater choice of partners .... but in the Middle East and Indian subcontinent, the figures have remained high.
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| Sometimes Its Best Not To See The Bride or Groom |
Cousin marriage generally, is also popular in Middle East, where it accounts for over half of all marriages in some countries.
In general there is no real medical or moral reason not to marry a cousin, but where its a first cousin marriage and the parents come from the same practise, then there are some issues to consider. For instance in India, where northern Indian Hindus treat all kinds of first cousin marriage as incest, but where Hindus in the south don't always take this view, and Muslims don't consider it any taboo .....
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| Consanguinity Rates Worldwide |
... then the practice of marrying your cousin, leads societies to what is termed high levels of consanguinity aka 'blood relationships' (which is the quality of being descended from the same ancestor as another person), in these communities, which is perhaps not healthy for population, or the individuals.
There is evidence that such marriages increase the risk of various genetic disorders in children with children of first-cousin marriages having an increased risk of genetic disorders, particularly if their parents both carry a harmful recessive mutation, while children of more distantly related cousins have less risk of genetic disorders. Research among Arab populations, and others worldwide has indicated that high degrees of consanguinity have an effect on some reproductive health parameters, such as postnatal mortality and rates of congenital malformations.
When the worldwide populations of homo-sapiens was small, such marriages or relationships must have been very common, indeed its been estimated that 80% of all the marriages in history may have been between second cousins or closer. However in the last few millennia, this has increasingly ceased to be the case, and the reason for such marriages is generally religious or cultural. For instance to preserve family wealth, strengthen family ties, or because its considered healthier. In the West, proportions of first-cousin marriage have declined since the 19th century, as social mobility allowed for a greater choice of partners .... but in the Middle East and Indian subcontinent, the figures have remained high.
Cousin marriages roughly doubled the risk of birth defects, though they remained rare, affecting around 6% of children born to cousins.
Marrying a first cousin means that they share 12.5 per cent of their
genetic material with each other ... but if they are double first
cousins (when two siblings of one family reproduce with two siblings of
another family), the resultant children are then related to each other
through both parents, and sharing the same grandparents. As a result,
double cousins are genetically equal to half-siblings, sharing double
the genetic material normally seen in first cousins i.e. 25 per cent
shared DNA.
If the whole family were related in this manner e.g. Two brothers married two sisters who were first cousins, and their children all married the others children then it wouldn't be long before they shared the majority of their DNA in the same manner as brothers and sisters. To see the effects of this take a quick look at the Hapsburgs, who literally bred themselves into imbecility and deformity by first cousin marriages.
Worldwide, more than 10% of marriages are still between first or second cousins while in some Arab countries, first cousin marriages may reach 25–30% of all marriages e.g. In Qatar, Yemen, and UAE, consanguinity rates are increasing in the current generation. In the UK, in the Pakistani immigrant population, about 55 - 60 per cent are reported as marrying a first cousin.
This latter figure has so concerned some, that in 2008 a government minister Phil Woolas, said that "If you have a child with your cousin, the likelihood is there'll be a genetic problem" and that such marriages were the "elephant in the room".
Update 18/02/2018: Bradford's Child Death Overview Panel has just reported that a significant number of child deaths in the town are a direct result of Asians marrying first cousins. Of the 69 child deaths investigated in 2018, 45 were of South Asian descent, with 30 of these having Chromosomal, Genetic, and Congenital anomalies. The panel are so concerned that it is suggesting 'genetic counselling' for Asian families to make them aware of the risks of marrying someone who shares the same ancestor ..... the elephant in the room just trumpeted.
If the whole family were related in this manner e.g. Two brothers married two sisters who were first cousins, and their children all married the others children then it wouldn't be long before they shared the majority of their DNA in the same manner as brothers and sisters. To see the effects of this take a quick look at the Hapsburgs, who literally bred themselves into imbecility and deformity by first cousin marriages.
Worldwide, more than 10% of marriages are still between first or second cousins while in some Arab countries, first cousin marriages may reach 25–30% of all marriages e.g. In Qatar, Yemen, and UAE, consanguinity rates are increasing in the current generation. In the UK, in the Pakistani immigrant population, about 55 - 60 per cent are reported as marrying a first cousin.
This latter figure has so concerned some, that in 2008 a government minister Phil Woolas, said that "If you have a child with your cousin, the likelihood is there'll be a genetic problem" and that such marriages were the "elephant in the room".
Update 18/02/2018: Bradford's Child Death Overview Panel has just reported that a significant number of child deaths in the town are a direct result of Asians marrying first cousins. Of the 69 child deaths investigated in 2018, 45 were of South Asian descent, with 30 of these having Chromosomal, Genetic, and Congenital anomalies. The panel are so concerned that it is suggesting 'genetic counselling' for Asian families to make them aware of the risks of marrying someone who shares the same ancestor ..... the elephant in the room just trumpeted.
Update 2022: This is an issue in the South Asian community world-wide, including Britain, so the BBC have a podcast on it. Of course the issue is still being ignored by white ministers who are afraid of inflaming the Asian communities.
Update 2023: The Born in Bradford study has just reported that ten years ago researchers found that about 60% of babies in the Pakistani community, had parents who were first or second cousins, but a new follow-up study of mothers in three inner-city wards, found that the figure has dropped to 46%.
Asian females higher educational attainment and aspirations, new family dynamics (with 'arranged' marriage and particularly with a marriage to first cousins resisted by younger British south Asians ... 'its gross'), and changes in immigration rules, making it tougher for foreign bides or grooms to come to the UK unless financial support is there, are thought to be possible reasons.
The fact that fewer and fewer relationships are between cousins makes me wonder whether this could be a contributing factor for our increased life expectancy? Also I'd be interested to know why marrying cousins is a tradition? The only reason that comes to mind is that of keeping money and values of the family in the family - selfish, misanthropic and hopefully self defeating motives.
ReplyDeleteIn the UK generally marrying first cousins is low (it was actually illegal for along time) ... the practise has increased because some estimates are that up to 70 per cent the UK Asian Muslim population married their first cousins. A 2008 analysis of infant mortality in Birmingham showed that "South Asian" infants had twice the infant mortality rate and 3 times the rate of infant mortality due to congenital anomalies ... enough said.
DeleteAnecdotally I know two south Asian immigrants who are married to their first cousins, and both have one child who has a congenital problem.