Answered by: Maulana Syed Johir Miah
Are the laws of hijab applicable between a man and his illegitimate daughter (from zinaa)? Can she live with him?
In the name of Allah, the Most Gracious, the Most Merciful
Sayyiduna Abu Huraira( رضى الله عنه )narrates that the Messenger (صلى الله عليه وسلم) of Allah said:
الوَلَدُ لِلْفِراشِ، ولِلْعاهِرِ الحَجَرُ
“The child will be attributed to the husband and the adulterer will receive the stone”.
The meaning of this Hadith is that the right of paternity will always be for the one to whom the mother of the child is married. Hence, paternity will not be established with the adulterer. If the woman is unmarried, the child will only be attributed to her.
Based on the above, it becomes clear that if one’s father had illegitimate children from another woman, then they will not be attributed to him. His illegitimate children will not inherit from him, neither is he, Islamically, considered the father of these children. As such, the other legitimate children of his will not be considered their stepbrothers or stepsisters; hence the rules of Hijab will have to be observed.
However, this does not mean that marriage between them is permitted due to the fact that one may marry a non-Mahram. The jurists (fuqaha) state that it is unlawful for one to marry one’s illegitimate daughter despite paternity not being established and her not inheriting from him.
The Majority of the scholars have declared with this verse,
حُرِّمَتۡ عَلَيۡكُمۡ اُمَّهٰتُكُمۡ وَبَنٰتُكُمۡ
Prohibited to you for marriage are: Your mothers, daughters, sisters,
وقَدِ اسْتَدَلَّ جُمْهُورُ العُلَماءِ عَلى تَحْرِيمِ المَخْلُوقَةِ مِن ماءِ الزّانِي عَلَيْهِ بِعُمُومِ قَوْلِهِ تَعالى
وبَناتُكُمْ فَإنَّها بِنْتٌ
The prohibition of marriage with a woman born out of one’s unlawful relationship, due to the generality of Allah’s statement: “Your daughters” because she (a girl born out of wedlock) is one’s daughter hence she will be included in this generality. 
The reason being is that (the son or daughter born out of wedlock) is in reality one’s own child.
However, precaution is important in regards to marriage, thus one cannot make an analogy on inheritance.”
What the above is trying to say is that an illegitimate child is in reality and physically one’s own child hence marriage is unlawful, for one cannot marry one’s own daughter. However, due to the fact that the child is Islamically considered illegitimate, Shariah did not establish paternity with the adulterer hence the child will not inherit from his father.
In conclusion, the rules of the Hijab do not apply between a father and his illegitimate female children.
Only Allah knows best
Written by Maulana Syed Johir Miah
Checked and approved by Mufti Mohammed Tosir Miah
Darul Ifta Birmingham
 Sahih Muslim, Hadith 1458, 1081/2
 Suratun Nisa, Verse 22
 Tafseer Ibn Katheer, 216/2
 Ahkamul Quran, 2/205