Final answer:
Henry's father likely put a button saying "I am Chinese" on him to avoid the discrimination specifically targeted at Japanese Americans and to clarify his son's ethnicity during a time of significant anti-Asian sentiment and legislation in the U.S.
Step-by-step explanation:
To answer the question: Why did Henry's father put a button on him that said "I am Chinese"? It is quite likely that this action was taken as a response to the discrimination and confusion surrounding Asian identities during times of significant anti-Asian legislation and sentiment. Specifically, during the late 19th and early 20th centuries in the United States, laws such as the Chinese Exclusion Act of 1882 and later on, the informal agreements regarding the Japanese, led to increased scrutiny and discrimination against Asians. To avoid the discrimination specifically targeted at Japanese Americans, Henry's father might have wanted to clarify his son’s ethnicity, given that Chinese and Japanese people were subject to different social and legal treatments at the time.
There was also the notion of 'paper sons,' where due to lost documents from the San Francisco Earthquake of 1906, many immigrants claimed relationship to American-born Chinese to claim citizenship. Identifying as Chinese therefore not only could be a statement of national pride but also a strategic move to navigate the societal and legal complexities of the time, which might have influenced Henry's father to label his son visibly as Chinese to protect him from the negative repercussions against Japanese individuals.