Preparations for the annihilation of the European Jews began in the summer of 1941. Here the activities of KdF and SS went hand in hand. Hence, more than ninety T4 men were eventually transferred to the east to carry out the final solution in the General Government. Friedlander's book is not without a few shortcomings, though. For example, he argues that the persecution and mass murder of the Gypsies in German-occupied Europe paralleled the fate of the Jews.
Recent scholarship disagrees here.
According to Guenter Lewy, there were notable differences between the Nazis's treatment of Gypsies and Jews. Lewy argues that the Nazis never had the intention to kill all or even parts of Europe's Gypsies and only a minority of German Gypsies was deported to Auschwitz-Birkenau. For example, in Norway the collaborationist government under Vidkun Quisling enacted a new, more radical sterilization law in June 1942 which allowed for compulsory sterilizations. In the wake of this law the annual number of sterilizations in Norway increased considerably. The eugenic movement there willingly supported Nazi population policy.