Most of his maternal cousins were breastfed by his mother and he was breastfed by his maternal aunt; what is the ruling on his brother?

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Check below answers in case you are looking for other related questions:
Attribution of an illegitimate child and rulings that result from that
She married the one who committed zina with her after she gave birth and the nifaas bleeding stopped

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Related Answers:
Ruling on marrying cousins
The sister of the wife’s grandfather and the sister of her grandmother are mahrams to the husband just as her paternal aunt and maternal aunt are mahrams to him
If the custom is for a girl not to marry her cousin, does he become a mahram for her?
Attribution of an illegitimate child and rulings that result from that
She married the one who committed zina with her after she gave birth and the nifaas bleeding stopped

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