The majority of children/offspring created from this practice are suffering.
They tend to become lost and feel like they don't belong anywhere or somewhere in between the middle.
They would much rather belong to one race, one group of people, rather than be drifted everywhere.
Maybe the parents don't know, but that is what's going on inside of these children/offspring, more chaos rather than harmony.
DNA and Soul are connected, so the more mixed it is, the more mixed everything else will become, including your mind.
In the movies and advertising with happy smiles maybe this is not visible, but it is true.
Also the majority of relationships and marriages of this practice don't last long and are unreliable, not a stable ground.
It's not about one is better than the other, it's about harmony.