tarred with the same brush
Having the same faults or bad qualities, as in He may be lazy, but if you ask me his friends are all tarred with the same brush. This term is thought to come from sheep farming, where the animals' sores were treated by brushing tar over them, and all the sheep in a flock were treated in the same way. The term was transferred to likeness in human beings in the early 1800s.
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