Beat me to it but yeah, he was a Sanger super/only fan. We think of the persecution against Jews and racism against Blacks was the bad stuff between the start of the 20th century and when Civil Rights was passed . . .the truth is that eugenics is older and way more of a bigger threat than most people realize.
Sanger's mistake was saying a lot of the quiet parts out loud. If she hadn't done that then nobody would know what her goals were. I remember when PP and other pro-infantcide types were angry that Sarah Palin chose to give birth to a baby with downs syndrome. These people are pro-choice only up to the point that a pregnant woman's choice goes against their choice.