Wiktionary
birds of a feather flock together
prov. People of similar character, background, or taste tend to congregate or associate with one another.
Usage examples of "birds of a feather flock together".
But as birds of a feather flock together, Madame and the Dauphine, the maid, and a few other like-minded women had formed a little clique centered upon the Private Cabinet of the Dauphine’.