The sexual drive is one of most important instincts of the human being and is a means of maintaining human generations.  It is one of the greatest blessings Allah has granted humans. The sexual drive commences in attraction to the opposite sex during puberty and teenage years. This attraction is instinctive, mental and physical which arouses one and results in "Sexual Behavior".  

Islam has endorsed satisfying the sexual desire only through the channel of marriage and has emphasized on it, and it has only allowed people to satisfy their sexual need through a sexual relationship with none other than their spouse.

In addition to permanent marriage, Islam has legislated temporary marriage with certain conditions as a way to satisfy sexual needs.  This is why marriage is the only means of satisfying sexual desire in Islam.   Also suppressing this desire has been sharply rejected and considered impermissible; instead when there is not an opportunity for marriage, Islam has called people to "Iste'faf" (Chastity).

The Holy Quran says: "Those who cannot afford marriage should be continent until Allah enriches them out of His grace."[1] Modesty which means to control the sexual desire is very beneficial while sexual perversion can be of great harm.

From the Islamic viewpoint, sexual perversion is known as the sexual behaviors which go further than one's nature and are accompanied along with stress and anxiety. An example for that would be engaging in incestuous sexual behavior (which includes looking   with immoral intentions, touching and kissing with lust, and intercourse) with the maharem, like one’s mother, sister, aunt and etc.

The effects of any type of sexual perversion and especially incestuous relationships can be greatly harmful to one's personal and social life and will entail severe spiritual and mental damages. This is why it has been heavily forbidden in Quranic verses and ahadith of the infallibles.[2] Also the punishment set for this act is more severe than that of sexual relationships with non Maharem and this indicates that the punishment for it in the hereafter is also greater.

In this regard the Quran says: " Forbidden to you are your mothers, your daughters and your sisters, your paternal aunts and your maternal aunts, your brother's daughters and your sister's daughters, your] foster- who have suckled you and your sisters through fosterage[3], your wives" mothers, and your stepdaughters who are under your care] born [of the wives whom you have gone into but if you have not gone into them there is no sin upon you and the wives of your sons who are from your own loins, and that you should marry two sisters at one time excluding what is already past; indeed Allah is all-forgiving, all-merciful)."[4]

In respect to this issue the Foqaha say: "If one commits incest with one of his maharem[5], like his mother or sister, he must be executed if the Muslim leader orders so."[6]

It is mentioned in the Islamic penal code that: "The punishment of committing incest in any form with the nasabi maharem (those maharem that are blood relatives like ones aunt or niece) is execution, whichever way it is done."[7] And there is no difference between men and women in regard to this ruling. Of course if one has, god forbid, committed such an act, he must repent to Allah and have hope in Allah's mercy, and it is not obligatory for him to cause his own execution by confessing to this sin.

But we must pay attention that this wrong act may entail special jurisprudential rulings in certain situations and it is obligatory to act accordingly, for example it is mentioned in the risalahs that: "If one commits incest with his paternal or maternal aunts prior to marrying their daughters, they will be unlawful[8] to him for the rest of his life (meaning that he can't get married to them."[9]