"After the eugenics movement was well established in the United States, it was spread to Germany. California eugenicists began producing literature promoting eugenics and sterilization and sending it overseas to German scientists and medical professionals.[4] By 1933, California had subjected more people to forceful sterilization than all other U.S. states combined. The forced sterilization program engineered by the Nazis was partly inspired by California's.[5]" WIKIPEDIA

This is from Wiki, have no other sources, sorry, but they link to plenty.

The Kaiser, Wilhelm II, wrote to the Swiss ambassador in December 1912:

[The unavoidable] racial war, the war of Slavdom against Germandom...[in which the] Anglo-Saxons with whom we are related by common ancestry, religion and civilisatory striving, allow themselves to be used as tools of the Slavs...if this question...cannot be solved by diplomacy, then it will have to be decided by armed force. The solution can be postponed but the question will arise again in 1 or 2 years. The racial struggle cannot be avoided - perhaps it will not take place now, but it will probably take place in one or two years.

In the same month, he also wrote:

Chapter 2 of the Great Migrations...is over. Now comes Chapter 3, the Germanic peoples' fight for their existence against Russo-Gallia. No further conference can smooth this over, for it is not a question of high politics, but one of race...for what is at issue is whether the Germanic race is to be or not to be in Europe.

The above could have been written by a Nazi during WWII. After the War, Wilhelm believed Germany's defeat was caused by the Jews, as he wrote in 1919:

The deepest, most disgusting shame ever perpetrated by a people in history, the Germans have done onto themselves. Egged on and misled by the tribe of Juda whom they hated, who were guests among them! That was their thanks! Let no German ever forget this, nor rest until these parasites have been destroyed and exterminated from German soil!

Again, he wrote in 1927:

The Hebrew race are my most inveterate enemies at home and abroad; they remain what they are and always were: the forgers of lies and the masterminds governing unrest, revolution, upheaval by spreading infamy with the help of their poisoned, caustic, satyrical spirit. If the world once wakes up it should mete out to them the punishment in store for them, which they deserve.

As you can see from the above the Kaiser held similar attitudes to Hitler regarding racial ideas in that he held the Slavs in contempt and was very anti-Semitic to the point of wanting the Jews to be exterminated. In viewing Germany's defeat as the work of Jews, that Jews were behind revolutions and also the Freemason ruling class of England, this was very similar to Hitler's view. Nazi thinking on race had antecedents in Imperial Germany.