Hi OP American living in the NL for over 10 years. Polish heritage. Brought my parents to Poland, they don't speak Polish, know a few recipes we use for Christmas, but that's about it. They told everyone they were Polish. I know they meant heritage but in no real way are they Polish. They probably couldn't find Poland on a map to be honest. Know nothing about the modern culture, politics, issues, famous places even. I love my parents deeply, and understand why Americans use xxx-american (I did it too once a long time ago). But you are not Dutch in any meaningful way and if you tell Dutch people you are Dutch, you are clearly using a 100% different definition than they are. They will assume that you speak Dutch, know Dutch culture, etc, and probably that you are a citizen. You should phrase it differently to non-americans, like my mom's family originally came from the Netherlands