No, but they are all just really close friends and get along very well.
No, they are not, but they are good friends.
None of them are brothers!
no
No the boys from one direction are not really brothers
No, none of the 1D boys are related
No.
Niall
No not all of them are.
No
All of them.
The one direction boys are not brothers and there is no sisters but the name of the boys are Zayn Harry Louis Liam Niall
No. When the boys were placed together as a band in 2010, Harry came up with the idea that they call themselves "One Direction." All the rest of the band agreed, and they became One Direction. They won't be changing their name anytime soon.
All of One Direction except for Niall James Horan have girlfriends.