There are lots of linkages, but basically they're highly inflammatory. For whatever reason, the oils that are the most shelf-stable are the most inflammatory ones.

The most common "seed oils" are

It seems like the typical extraction process (expeller pressing) and subsequent processing are probably for a good bit of the problem, so you don't need to worry about consuming the oil if it's still part of the whole food.

Similarly, if you can find a cold pressed version of the oil, it's probably not as bad.