Final answer:
Without the specific context of Rachel's story, we cannot provide the reason behind her wish to be 102 years old, as it is not present in the provided references.
Step-by-step explanation:
The information provided does not contain details about why Rachel wishes she were 102 years old. This might be from a text not included among the references. Therefore, to offer an accurate and helpful explanation, the complete context of Rachel's situation from the relevant story or literature is necessary. Based on the given extracts, multiple characters reflect on their lives, dreams, and experiences with aging, but without the specific context of Rachel's story, we cannot confidently provide the reason behind her specific wish to be 102 years old.