People who believed that biological engineering should be used to promote the breeding of "desirable" races and limit the reproduction of "unfit" races were called:

People who believed that biological engineering should be used to promote the breeding of "desirable" races and limit the reproduction of "unfit" races were called eugenicists.

Developed largely by Francis Galton in 1883, eugenics was especially common in Nazi Germany during WWII. The ethics of this "genetic cleansing" has been highly debated since its creation.

Hope I could help!

Ibelieve the answer is benjamin franklin.