If someone X is a relative of someone Y then Y is a relative of X. If someone X is a child of someone Y then Y is a parent of X. If someone X is a parent of someone Y then Y is a child of X. If someone X is a parent of someone Y then X is a relative of Y. If someone X is a male child of someone Y then X is a son of Y. If someone X is a female child of someone Y then X is a daughter of Y. If someone X is a male parent of someone Y then X is the father of Y. If someone X is a female parent of someone Y then X is the mother of Y. John is male. Mary is female. Bill is male. Tom is male. Bob is male. Sue is female. John is a child of Mary. Bill is a parent of John. Sue is a child of Tom. Bob is a parent of Mary.