I think that adopting biological definitions of settler/indigenous identities is not just un-Marxist, it has disturbing echoes of race realism. Whether someone is a settler or not shouldn't be a question of genetics, it should be defined by how they relate to the settler state and settler ideological and cultural values. Ultimately it's a matter of how someone self-identifies, and whether they see themselves as part of the historical settler project or as outside or opposed to it. It has to do with the community they associate with and grew up in. Indigenous identity can be erased by assimilation but the reverse is also true, that people with settler ancestry can be deprogramed and learn to integrate into an indigenous culture and community (of course, as some comrades have pointed out in their replies below, this can only happen AFTER the stolen land has been returned to indigenous people).