A bad embouchure can put pretty much any brass instrument a full semi-tone out of tune. Trombone is not noticeably different in a beginner band. In my experience it's the beginner French Horn that's usually most out of tune.

But brass being out of tune is not as hard on the ears as the squeaks from a beginner clarinet or saxophone...

Probably the most parent friendly is the flute. It's really hard to get good volume out of a flute so beginners are really quiet and inoffensive. :)