I've dug through interviews, liner notes, and fan Q&As enough to feel confident saying this: Noah Sebastian is best known as the vocalist and songwriter for 'Bad Omens', and he presents publicly as an American artist who keeps a lot of his private life private. There isn't a detailed, verified public record of his full ethnic ancestry the way some celebrities openly share; most official bios and music press focus on his music, touring, and creative influences rather than a breakdown of family lineage.
That said, from what he has shared in interviews and social posts, family played a role in his early life — there are mentions of parents being supportive of his musical ambitions and of growing up in an environment where art and music mattered. Fans sometimes speculate about heritage based on appearance or anecdotal comments, but those remain speculation. For anyone curious about concrete ethnicity or family origins, the most reliable sources would be direct statements from him or family, which he hasn't deeply publicized. Personally, I respect that privacy and prefer to focus on how his background shaped his sound and lyrics, which feel honest and lived-in to me.