Answered by Ustadh Tabraze Azam
Question: Assalam alaikum,
If a brother and sister had the same mother but different fathers, and were NOT breastfed then will they be mahram (unmarriageable) to each other?
Answer: Assalamu alaikum wa rahmatullah,
I pray that this message finds you well, insha’Allah.
A half-sibling is one who shares a parent with you, and such a person is from your unmarriageable kin (mahram). This is contrary to your stepbrother or stepsister who are not considered as such. [Kasani, Bada`i al-Sana`i fi Tartib al-Shara`i]
Allah Most High said, “You are forbidden to take as wives your mothers, daughters, sisters, paternal and maternal aunts, the daughters of brothers and daughters of sisters, your milk-mothers and milk-sisters, your wives’ mothers, the stepdaughters in your care– those born of women with whom you have consummated marriage, if you have not consummated the marriage, then you will not be blamed– wives of your begotten sons, two sisters simultaneously– with the exception of what is past: God is most forgiving and merciful.” [4.23]
Please see: Who is Mahram and: Are My Half-Brothers Unmarriageable Kin (mahram)?
And Allah alone knows best.
في البدائع للإمام الكاساني: وتحرم عليه أخواته وعماته وخالاته بالنص وهو قوله عز وجل: {وأخواتكم وعماتكم وخالاتكم} سواء كن لأب وأم أو لأب أو لأم لإطلاق اسم الأخت والعمة والخالة، ويحرم عليه عمة أبيه وخالته لأب وأم أو لأب أو لأم اهـ.
wassalam,
Tabraze Azam
Checked & Approved by Shaykh Faraz Rabbani