Listbox items become too high for no reason?

Hello the screenshot explains it:

Why are do the Items become so tall? I do no positioning myself:

    <ListBox Margin="6" ItemsSource="{Binding RelativeSource={开发者_如何学运维RelativeSource Mode=FindAncestor, AncestorType={x:Type UserControl}}, Path=Segments}">
    </ListBox>

No ItemTemplate either I'm relying on default ToString() behaviour.

Sorry, I found the problem. Each Line is surrounded by newline characters.

I didn't see it immediately because the data is returned via IPC call from external program.