Race vs. Gender in Nazi Germany & Modern America

If there are biological differences of race, why is it invalid to treat people of different races in different ways but valid to treat different sexes in different ways? What arguments against differential racial treatment don't also work against differential gender treatment? I'm not sure there are any. Might this mean that people who accept one are likely to accept the other - that people who accept differential treatment of the sexes are more likely to accept differential treatment of races?

 

Book Notes: Race vs. Gender in Nazi Germany & Modern America: Christian Nationalists Using Biology to Define Social Roles