I came up with a new idea: survival of the fittest. I read that Darwin said something along the lines of "The fittest is not the strongest, nor the most intelligent, but the one most susceptible to change" - basically the one that can adapt to changes in the tribe/society/country the best of all. So, what better way to have the best of humanity have children than to promote noble people in everyday culture and society. Instead of focusing on the negative - "X, Y, and Z will not have children" - we can focus on the positive - "Let's make sure A, B, and C are more likely to have children".
Ultimately, this is not just for the betterment of humanity, but for everything that humanity comes in contact with to profit as well.