Genocide is defined by intention to remove population or preventing their breeding. It has nothing to with who attacked who first or whether something ia nation state or not.
EU as in European Union came to be long after colonization and have member states that were colonies of someone else.
Did France give up its colonies already? Minister of the Interior and Overseas Territories is a title in France. What about the Dutch? Those don't count, I'm guessing, because the colonies have been subdued and don't show up in the news feed.
So basically, EU did not actively enslaved or colonized anything. But, past colonies of some EU member states mean that there can not be genocide anywhere outside of Europe.
EU as in European Union came to be long after colonization and have member states that were colonies of someone else.