When it comes to race, can any one human being truly say they are 100% one particular race?

Such as 100% white, black, asian etc?

This was an interesting question a follower of mind asked on Twitter. Its not something I have considered before. But taking into account how long humanity is around, I’m thinking it is possible that quite a lot of us could have at least a distant ancestor from a racial identity in which we currently don’t identify as.