Statement 1: Given that X is the brother of Y, and Y is the brother of Z, we know that all three individuals are siblings. However, the gender of only X and Y is specified. Without knowing whether Z is male or female, we cannot determine whether Z is the brother or sister of X.

Statement 2: Simply stating that X, Y, and Z are siblings does not provide information about their genders. Without knowing the gender of Z, we cannot determine whether Z is the brother or sister of X. Combining the two statements does not resolve the ambiguity regarding Z’s gender, so we cannot definitively answer the question.