SSC CPO 10 Nov 2022 Shift 2 Paper

There are six children playing ludo, namely 1, 2, 3, 4, 5, and 6. 1 and 5 are brothers. 6 is the sister of 5. 3 is the only son of 1's father’s brother. 2 and 4 are the daughters of the only brother of 3's father. How is 4 related to 1?