It is prohibited by God to marry or to have sexually relationship with your kin.
Let us look at some information of marrying your own siblings, people who are first, second and third degree of consangunity from you. Let us discover some information about this. Marriage between first cousins, doubl3 the risk of birth defects, say researchers.
Study of 13,500 babies born in Bradford concludes cultural pratice in Pakistan community outweighs effects of deprivation, marriage between first cousins double the risks of children being born with birth defects( according to the study seeking answers to the higher than expected rates of deaths and congenital abnormalities in the babies of Pakistan community. Leviticus 18 verse 6 says, none of you shall approach yo any that is near of kin to him, to uncover their nakedness: I am the lord.
Verse 7 says, the nakedness of thy father,or the nakedness of thy other shalt thou not uncover, she is thy mother, thou shalt not uncover her nakedness.
Verse 8 says, the nakedness of thy fathers wife, shall thou not uncover; it's thy fathers nakedness.
Verse 9 says, the nakedness of thy sister, the daughter of thy mother, whether she be born at home, or born abroad, even their nakedness thou shalt not uncover.
Verse 10 says,The nakedness of thy son's daughter's daughter, even their nakedness thou shalt not uncover, for theirs is thine own nakedness.
Verse 11 says, the nakedness of thy father's wife's daughter, begotten of thy father, she is thy sister,thou shalt not uncover her nakedness.
Verse 12 says, thou shalt not uncover the nakedness of thy father's near kinswoman.
So, it is prohibited from God to have sexual relationships with the your kin. And science tells us an information that if you marry the nearest of your kins,it is not something good because you might end up having babies with defects. Mental and physical if you will accept an advice you better wait for a man that is not a kin.