[Jack_]

Actually I guess the real question is what exactly was asked of the family member and if there was any malicious intent. There's a difference between

'Do you know someone called Mike, and does he know a girl called Mollie?'

and

'Just to let you know your daughter/sister/whoever has been stealing some girls pictures and duping people on an Internet forum for four years. Bye'

Both unacceptable but one is worse than the other. The intent is quite important here if bans are actually being considered.