It means people and animals tend to stick to their own kind.
birds of same feather flock together
You're Ugly
It means people with similar interests or shared characteristics group together
People tend to be drawn to others who have similar interests. They can also be attracted to people with similar beliefs, morals, and standards for living. This can be both good and bad. On the good...
Birds of a feather flock together means that people who have many similarities intend to hang out together.