Finally I am done with 25 posts and am free to post links
"It should be mentioned that some narrations have been reported about the dislikeability of marrying relatives but these narrations are not authentic. However, some scholars are of the opinion that it is disliked to marry relatives based on these** inauthentic narrations**.
Nonetheless, some medical studies showed that marrying relatives may lead to the transfer of some hereditary diseases. However, this is not true all the time. The medical studies which were carried out recently stated that the danger of the spouses who are relatives having children with deformations or hereditary diseases reaches 7% or 8%, whereas the percentage in spouses who are not relatives is only 5%.
This study advised doctors not to immediately discourage relatives from marrying each other, and that instead they should advise them to carry out medical tests before marriage.
It is worth mentioning here that marrying relatives is absolutely permissible and there is no general harm in it. It is impossible for Allaah to*** render something absolutely permissible***, which would be a general harm for all people. Allaah Knows best. "
Islam Web - Fatwa Center - Prophetic narration about the superiority of marrying cousins
"…On the other hand, cousins are not close enough relatives to be vulnerable to the same high risk factor of genetic problems. However, although cousins are allowed to get married, due to the lower risk of having genetic problems in their children, the presence of even this low risk of having such problems made such marriage not the best recommended. Omar Ibn Al Khattab said: ‘Marry the strangers to become healthier.’
The same risk, of having health problems with the children if one marries a cousin, actually happens, if one marries a woman over 35 years old. The risk is also the same if a man or a woman chooses a spouse with a family history of a certain disease. Still, the possibility is not strong enough to incriminate this marriage.
Nevertheless, one should try to make use of all possible precautions. Among these precautions, are the modern scientific techniques of genetic tests. These are now available, for marrying couples, to detect the possibility of facing such troubles. Marrying couples can undergo these tests before they getting married. These tests are recommended, not only for cousins, but also for everybody, because even strangers might be exposed to such problems. Thus, the possibility of having a genetic problem in marrying a cousin is not, exceptionally, strong enough, to make it prohibited.
Another important factor, worth mentioning, is the nature of the oriental societies. They were mostly, some are till now, tribal. People only get to know one another through family circles. This permission corresponds with the general policy of the Islamic law that tends towards widening, rather than narrowing people’s choices in life, unless a thing is a ‘real’ threat. "
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