In the same way as object oriented languages represent inheritance attributes can be inherited through generalization. This is a done through a IsA relationship between two or more entities.

In a entity-relationship diagram we show this be drawing a relationship with a triangle with the label IsA and then connecting it to the relevant entities. On corner (the "top") is connected to the "parent" entity (the one which we inherit attributes from) and then the opposite face is connected to any entities which inherit it's attributes.