Conditions: I is the brother of J. K is the father of I. L is the brother of M and M is the daughter of J. Under these conditions, who is I to L?

Introduction / Context:
This blood relation problem gives a set of conditions about four people: I, J, K, L and M. You are told how they are related as siblings, parents and children, and then asked to determine how I is related to L. The main skill needed is to recognise which generation each person belongs to and how children of one person relate to siblings of that person.

Given Data / Assumptions:
- I is the brother of J. - K is the father of I (and therefore also the father of J). - L is the brother of M. - M is the daughter of J. - We assume usual definitions: father, brother, daughter, etc.

Concept / Approach:
First, place K at the top as the father. Then place I and J as siblings in the next generation. Next, J has a daughter M, so M is one generation below I and J. L is M's brother, so he is also a child of J, at the same generation as M. Once this family structure is in place, you can examine how J's children relate to J's brother I. Typically, the children of your sibling are your nieces and nephews, meaning you are their uncle or aunt.

Step-by-Step Solution:
Step 1: From I is brother of J and K is father of I, we place K as parent, with children I and J in the next generation. Step 2: From M is daughter of J, we place M as J's child, one generation below I and J. Step 3: From L is brother of M, L is another child of J, in the same generation as M. Step 4: So J's children are M (daughter) and L (son). I is J's brother, so I is the paternal uncle of M and L. Step 5: The question asks: who is I to L? Since L is the son of J and I is J's brother, I is L's uncle.

Verification / Alternative check:
Sketch a family tree: at the top, K; next level, K's children I and J; below J, his children M and L. The relationship lines show that I is one generation above L and is a sibling of L's parent. By definition, a sibling of a parent is an uncle (if male) or aunt (if female). Since I is described as brother of J, we know I is male, so he is specifically an uncle to L.

Why Other Options Are Wrong:
- Grandfather: A grandfather would be the father of L's father or mother. That role is K, not I. - Son: I is clearly one generation above L, not below. - Brother: A brother of L would share the same parents and generation. I belongs to the previous generation and is the brother of J, not of L. - Cousin: Cousins are children of siblings, but here, I is the sibling of J, not the child of another sibling.

Common Pitfalls:
Students sometimes mistakenly treat I and L as cousins because they share a common ancestor K, but cousins are defined as children of siblings, not siblings of parents. Another common error is to lose track of which child belongs to which parent and misplace M and L in the diagram. Always anchor the parent–child relations first and only then deduce cross-generational relationships.

Final Answer:
I is L's uncle.