Question: Islam states that the human race multiplied from Adam and Eve. Does this mean the direct children of Adam and Eve married their own sisters? Does Islam permit marriage between biological siblings? A friend of mine from another faith asked this; please provide an explanation.
– M. Tawfiq Ahmed, Dammam.
Answer: The Islamic doctrine holds that the human race originated solely from Adam and Eve. Since God did not directly create any other couples besides these two, marital unions could only have taken place between brothers and sisters.
If one were to ask today whether marriage between siblings is permissible, the answer would be that it is not allowed.
When does an act become a sin? It becomes a sin if God forbids it; if He does not forbid it, it is not a sin.
In the early days of Islam, neither alcohol nor usury (interest) was prohibited. If anyone had died during that period while consuming alcohol or dealing in usury, they would not have been considered sinners in the eyes of God, because they did not engage in those acts after the prohibition was issued.
This is not merely a matter of faith-based reasoning; it is a logically sound argument.
Consider a government enacting a law banning the sale of Pan Parag (chewable tobacco). No action would be taken against those who sold it before the law was enacted; only those who sell it after the law comes into effect would be held liable.
When only a single couple existed on earth, Allah permitted marriage between brothers and sisters. This was necessary for the human race to multiply. Those who entered into such marriages when He permitted them did not commit a sin.
Today, however, He has prohibited such marriages. There was no necessity to permit it. It becomes an offense only if done after it has been prohibited.
No sensible person would agree to using an act performed before the ban as a precedent after the ban has been imposed.