Flex family - inheritance question

Hello guys, we are running WebCenter SItes 11G R1, and we have a question related to how the inheritance works on flex families:

We are using a flex family called Tag to represent tagging in our site (in order to "tag" an asset, and later on, use that tag information to conduct a search), and we have some problems when try to execute a search based on this attribute.

Being more specific, we have a Product flex family and It has five parent definitions (category subcategory, main group, sub group and product group) and each of these has its own attribute Tags (of type Tag that we mentioned previously). So, when we assign some tag asset to a category asset, and execute a search, some of their child elements inherit this value ( only some... not ALL of their descendants share the values).