It would ignore reality to suggest that racial and ethnic prejudices do not exist or that all manifestations of those prejudices have been eliminated. There is a risk that a child living with a stepparent of a different race may be subject to a variety of pressures and stresses not present if the child were living with parents of the same racial or ethnic origin.

The question, however, is whether the reality of private biases and the possible injury they might inflict are permissible considerations for removal of an infant child from the custody of its natural mother. We have little difficulty concluding that they are not. The Constitution cannot control such prejudices but neither can it tolerate them. Private biases may be outside the reach of the law, but the law cannot, directly or indirectly, give them effect….

This is by no means the first time that acknowledged racial prejudice has been invoked to justify racial classifications….

Whatever problems racially mixed households may pose for children in 1984 can no more support a denial of constitutional rights than could the stresses that residential integration was thought to entail in 1917. The effects of racial prejudice, however real, cannot justify a racial classification removing an infant child from the custody of its natural mother found to be an appropriate person to have such custody.