Final answer:
Michelle and her brother's different speech patterns from other family members can be attributed to sociolinguistic factors, language ideology, and code switching, reflecting individual experiences and social interactions.
Step-by-step explanation:
Michelle and her brother likely speak differently from their other family members due to various sociolinguistic factors. Language acquisition is influenced by a combination of personal interactions, cultural norms, and individual experiences, which may vary greatly even among members of the same family. The notion that American men and women have distinctive styles of speech is a prevalent language ideology in American culture. Despite this common belief, research, such as the meta-analysis by psychologist Janet Hyde, suggests that gender differences in language use are minimal. Additionally, the linguistic phenomenon of code switching might explain why Michelle and her brother's speech patterns differ from their family. Individuals often adjust their speech, consciously or unconsciously, according to the social contexts they find themselves in, which could account for the differences in the way family members speak.