Determining Relationships
Rules For Determining The Relationship Between Two People
There are many charts that show the relationships between two people. However, there are a few simple rules so that you can apply to any people.
- Step 1: Find the common ancestor.
- Step 2: Determine how many generations down each person is from the common ancestor.
- Example 1: If the common ancestor is a a parent, then the number of generations is 1 for the child and 0 for the parent.
- Example 2: For first cousins, the common ancestor would be a grandparent and the number of generations would be 2 for each person.
- Step 3: Apply these rules in this order:
- Rule 1: If the number of generations for either person is 0, then you have a parent, grandparent, great grandparent relationship. Use the number of generations for Person 2 (the other person) to determine the specific relationship.
- If generations = 1, then Person 1 is the parent of Person 2 and Person 2 is the child of Person 1.
- If generations > 1, then Person 1 is the X great grandparent of Person 2 and Person 2 is the X great grandchild of Person 1 where the number of “greats” is equal to Person 2’s generations minus 2. Note: For grandparents/grandchild this value will be 0.
- Rule 2: If the number of generations is 1 for either person, then you have an sibling or an aunt/uncle and niece/nephew relationship. Use the number of generations for Person 2 to determine the specific relationship.
- If 1, then the people are siblings
- If >1, then Person 1 is the great aunt/uncle of Person 2 and Person 2 is the great niece/nephew of Person 1 where the number of “greats” is equal to Person 2’s generations minus 2. Note: For aunts/uncles this value will be 0.
- Rule 3: If the number of generations is greater than 1 for both people, then you have a cousin relationship. The number of generations will determine the specific relationship.
- The people are X cousins Y times removed where X is equal to the number of generations for the person with the least number of generations minus one and Y is the difference between the number of generations for Person 1 and Person 2. Note: When the number of generations are the same, there are 0 removed and the two people are simply X cousins.
- Note: Typically X cousins are referred to using ordinal numbers (E.g. 1 becomes 1st, 2 becomes 2nd, etc.).
- Rule 1: If the number of generations for either person is 0, then you have a parent, grandparent, great grandparent relationship. Use the number of generations for Person 2 (the other person) to determine the specific relationship.