Salam Alaykum ..
Relatives who fall into the category of being mahrams are those male relatives mentioned literally in the Qur'an, in the context of explaining in front of whom women must practice hijab. Allah Almighty commands the Prophet Muhammad (peace and blessings be upon him) to enjoin modesty upon both the believing men and the believing women as follows:
[Say tothe believing men that they should lower their gaze and guard their modesty: that will make for greater purity for them: And Allah is well acquainted with all that they do.
And say to the believing women that they should lower their gaze and guard their modesty; that they should not display their beauty and ornaments except what (must ordinarily) appear thereof; that they should draw their veils over their bosoms and not display their beauty except to their husbands, their fathers, their husband's fathers, their sons, their husbands' sons, their brothers or their brothers' sons, or their sisters' sons, or their women, or the slaves whom their right hands possess, or male servants free of physical needs, or small children who have no sense of the shame of sex; and that they should not strike their feet in order to draw attention to their hidden ornaments. And O you Believers! turn you all together towards Allah, that you may attain Bliss}(An-Nur 24:30–31)
In verse 31, we note that the believing women are being given the permission to beautify themselves and to feel at ease interacting with several categories of men who qualify as their mahram. In addition to all of a Muslim woman's male blood relatives being mahram to her (her father, brother, uncles, etc.), there are also males who become mahram to her through marriage (her husband's father, her son, etc.). A Muslim woman is forbidden from marrying a man who is mahram to her. Similarly, a Muslim man, by virtue of being a mahram to women blood relatives, is forbidden from marrying his father's wife, his mother, his grandmothers, his sisters, his sister's and brother's daughters, his daughters, his granddaughters, his aunts, and even his wife's mother.
Wasalam 3nodding
