I have a suckling brother who is 25 years old, just as me. He has older brothers. Are they my brothers too? Am I required to wear the hijab in front of them?

All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

If you were both suckled by your mother or any woman other than his mother, then brotherhood through suckling is confined to him alone, apart from his brothers. Thus, they are non-Mahrams (permanently unmarriageable) to you, and you should wear hijab in front of them.

If you were both suckled by his mother, then his brothers are your brothers as well, whether they are older or younger than him because all of you were suckled by the same woman. The rule concerning this is the verse in which Allaah Almighty says (what means): {your sisters through nursing.} [Quran 4: 23]

Allaah Knows best.