Answer:
During the 19th century and the first half of the 20th, there was a rise in Europe of eugenics, a racist and racially charged scientific discourse (now absolutely discredited) that stipulated that certain “races” (a concept that has also been discredited) were inherently superior to other races (white and European being supposedly superior), and, for that reason it was their responsibility to spread their allegedly superior genes and culture all around the world, a fact that made imperialist and colonialist injustices more palatable to these so-called superior races.