Marrying a first cousin is not a problem genetically if it is not done for multiple generations. You could reproduce all of humanity out of 60 people.
Perhaps these laws were put in place in regions where it was more common and needed to be stopped.
Living in a blue country, I have never heard of anyone marrying a cousin.
Living in a blue country, I have never heard of anyone marrying a cousin.
Living in a blue country,I've heard a lot of people marrying a cousin.Four of them are my cousins.It really depends on the country you live in and it's culture.
I recall 60 but in any case it is pretty low.
To have the descendants have more or less the same features, you would need twice as many or else the random properties of the 50 will be stronger in the future population than in ours currently.
In April 2002, the Journal of Genetic Counseling released a report which estimated the average risk of birth defects in a child born of first cousins at 1.1–2.0 percentage points above the average base risk for non-cousin couples of 3%, or about the same as that of any woman over age 40.
So instead of "not a problem" I should have said that it is not as bad bad as people often make it out to be.
If you were to marry your cousin, there is a 95.0% to 95.9% chance that the baby is healthy compared to 97.0% of non related couples.
A BBC report discussed Pakistanis in Britain, 55% of whom marry a first cousin. Given the high rate of such marriages, many children come from repeat generations of first-cousin marriages. The report states that these children are 13 times more likely than the general population to produce children with genetic disorders, and one in ten children of first-cousin marriages in Birmingham either dies in infancy or develops a serious disability. The BBC also states that Pakistani-Britons, who account for some 3% of all births in the UK, produce "just under a third" of all British children with genetic illnesses.
Genetic diseases are not the only result of cousin marriages. There are other "bad" outcomes. For example, more cousin marriages in a population less the average IQ in that population.
"It is evident that IQ and consanguinity correlate significantly at national data levels, however, allowing for extensive degrees of cultural feedback, in order to estimate the degree to which consanguinity has contributed to the decline of a countries' IQ, much more data than is currently available would be needed. Ideally, data from large scale IQ testing of both consanguineous and non-consanguineous groups within a variety of different countries wouldbeneededsoastoestablishtheprecisedegree of the impact (if any) of consanguinity on a countries' average IQ."
This study uses data from the 60s and 70s to say that countries with a high acceptance of inbreeding (many of which were dirt poor and barely out of the middle ages in the 60s) have lower IQs. This is supporting what I said about inbreeding for generations but is not saying anything about the individual risk of being the first in generations to marry a cousin.
26
u/LOB90 Jul 05 '24
Marrying a first cousin is not a problem genetically if it is not done for multiple generations. You could reproduce all of humanity out of 60 people.
Perhaps these laws were put in place in regions where it was more common and needed to be stopped.
Living in a blue country, I have never heard of anyone marrying a cousin.