General Introduction:

 In some of his Prophetic Hadith, Allah’s Messenger, (PBUH), determined the practical aspects of the laws of genetics. It is well known that a fertilized ovule is a cell with a nucleus and chromosomes that include genes. The number of pieces of information that the genes have is too great. Only 800 of these genes have been so far discovered. The genes in a sperm combine with those in the ovule and produce a fertilized ovule. To this effect, Allah, All-Mighty, says

“Verily, We have created man from (drops) of mixed semen (sexual discharge of man and woman) in order to try him. So We have made him able to hear an see.”

[LXXVI; 2]

Results of marriages among first-degree relatives:

 Geneticists confirm that marriages among first-degree relatives transfer genetic defects, weakness, illnesses, diseases, and frailties to the next generations at a ratio of 50%. Marriages between second-degree relatives transfer genetic defects at a ratio of 12%, and between third-degree relatives 6%. This is why Allah, All-Wise, says,

“Forbidden to you (for marriage) are your msh3er, your daughters, your sisters, your fathers’ sisters, your msh3er’ sisters, your brother’ daughters, your sisters’ daughters, your foster msh3er who gave you suck, and your foster milk suckling sisters.”

[IV; 23]

 However, with marriages among fourth-degree relatives or non-relatives the ratio of transference of genetic defects is minimized. In this context, Omar bin Al-Khattab, may Allah be pleased with him, was quoted as saying,

“Seek marriage to non-relatives in order not to have weak generations.”

[Narrated by Ibn Hajar in his book “Talkhees Al-Habeer” (3/146)]

 In other words, the more distant the kinship between husband and wife is, the stronger the next generations are. Omar, may Allah be pleased with him, also said,

“Do not marry a relative of (your) relatives, for (if you do), children will be born weak.”

[An-Nihaya Fee Ghareeb Al-Hadith (3/106)]

 In the same context, Allah’s Messenger, (PBUH), says,

“Choose (proper msh3er) for your sperms, for women give birth (to children that are) like their aunts and uncles (i.e. like their mother’s brother and sisters).

[Ibn Majah (1968), Al-Hakim (2687), Al-Baihaqi (13536), and Ad-Darqutni (198)]

 That is why common people usually say:
“Like child like uncle or aunt (on the mother’s side).”

 Allah’s Messenger, (PBUH), also says,

“Seek proper msh3er for your sperms, for a man is probably like his uncles (on his mother’s side).”

[Kashf Al-Khafa’ (960) and (2917), Ahmad (24654) as, “If the woman’s fluid dominates, the child is like his uncles on his mother’s side; but if the man’s fluid dominates, the child is like him (i.e. like his father).”]

 ‘A’ishah, may Allah be pleased with her, also quoted Allah’s Messenger, (PBUH), as saying,

“Choose (proper msh3er or fathers) for your semen (male or female sexual discharge), and marry the proper ones and give them (your daughters) in marriage.”

[Narrated by Ibn Majah (198), and Al-Baihaqi (13536)]

 Generation improvement is the best thing that genetics can do. In other words, genetics should lead to production of new generations with higher mental abilities and better physical and psychological health. This is exactly what Allah’s Messenger, (PBUH), meant by his Prophetic Hadith and Tradition.

How to choose your wife:

 In the light of the above-mentioned Prophetic Hadith and Tradition, and according to the teachings of Islam, parents have great many rights on their children, but children also have a great many rights on their parents, first and foremost of which is to be careful in choosing proper msh3er or fathers for them before they come to this world.

 Before a man chooses a wife that will be his partner in life and his children’s mother, he has to be very careful, and he has to follow Prophetic Sunna and Tradition, which make clear that if a man marries a woman for her beauty, Allah, disgraces him; if he marries her for her wealth, Allah impoverishes him; if he marries her for her high social rank, Allah degrades him; but if he marries her for her righteousness, religiousness and devotion, Allah makes him prosperous and happy.

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