Final answer:
Johan Lavatories' theory appears to be a misunderstanding, as no individual by this name is known to have developed such a theory. However, historical pseudoscientific beliefs implied that people with light skin were more intelligent, which has been disproven by modern research.
Step-by-step explanation:
Under Johan Lavatories' theory, which is a misinterpretation as no well-known figure by that name established a racial theory, people with light skin were erroneously thought to have higher intellect due to pseudoscientific beliefs and racial assumptions. Such beliefs were associated with eugenics, a discredited field that attempted to prove innate racial differences and advocate for white supremacy by using flawed methods like craniometry to make false correlations between race, brain size, and intelligence. None of these beliefs hold any scientific validity and have been refuted by modern research which shows that intelligence is not determined by race but is influenced by a variety of environmental factors, including access to education.