Within a family I have personally observed is that siblings get one another's nerves at times and that this is normal. Older siblings can also go through an intolerant and moody phase with younger siblings.
Outside the family with our DD I have found it depends on the peer group, at regular public elementary DD would get dinged all the time on group projects and was labeled as being a child that didn't work well with others.
At drama camp and then over the past 2 years with CTY camps we got the exact opposite feedback - she was a natural leader who treated others with compassion and helped others along at time when they weren't getting it.
There is a difference between telling the honest truth and being brutally honest to savage someone's feelings obviously. If I saw my DD behaving that way I would have no compunction whatsoever in showing my DW the difference between the two and I would not consider that act to be suppressing or gagging my DD in any way. Rather it would be steering her towards behaving with decency and compassion - the 'use your superpowers for good not evil' talk.
YMMV
