It is natural to lump things together as we make connections. When we take in new information or meet new people, we attempt to make the new fit with our understanding that we already have. Or a category we are already familiar with.
But just because it’s natural doesn’t mean we should go with it. Each person is unique. Just because they believe one thing or fit in a certain category, does not necessarily extend out in the patterns that we have experienced before or thought we knew.
Obvious, and yet I am still amazed at how many times I assume x when I know y. Acknowledging is one important step to an open mind.