I went to a university in the US where many students have Dutch ancestry. (The school is tied to a church denomination that got its roots in the Netherlands.) It's pretty typical there for people to say "I'm Dutch" even if they have to go back several generations to get to the Netherlands. Then my dorm had an international student from the Netherlands, and that really illuminated the cultural appropriation you talked about in this article! I don't remember if I changed my phrasing as a result of that experience, or if I'd always said it like this, but my go-to is just "I have Dutch ancestry".