1. What is the Ancestry DNA Relationship Calculator?

The Ancestry DNA Relationship Calculator estimates the degree of relationship between two individuals based on the amount of shared DNA measured in centimorgans (cM). It uses a logarithmic scale to determine how closely related two people are.

2. How Does the Calculator Work?

The calculator uses the relationship formula:

Where:

• \( \text{shared\_DNA} \) — Amount of DNA shared between two individuals (cM)
• \( \text{total\_DNA} \) — Total amount of comparable DNA (cM)

Explanation: The logarithmic scale reflects how DNA is inherited in halves with each generation (parents share 1/2, grandparents 1/4, etc.).

3. Importance of Relationship Calculation

Details: Accurate relationship estimation helps in genealogy research, understanding family connections, and identifying unknown relatives through DNA matches.

4. Using the Calculator

Tips: Enter the shared DNA in centimorgans (cM) and the total comparable DNA. Both values must be positive numbers, and shared DNA cannot exceed total DNA.

5. Frequently Asked Questions (FAQ)

Q1: What is a centimorgan (cM)?
A: A centimorgan is a unit of genetic linkage that measures DNA segment length. Longer shared segments indicate closer relationships.

Q2: What are typical shared DNA amounts?
A: Parent-child share ~3400cM, full siblings ~2600cM, first cousins ~850cM, second cousins ~230cM.

Q3: How accurate is this calculation?
A: It provides a good estimate but actual relationships can vary due to random DNA inheritance patterns.

Q4: What if my shared DNA is very low?
A: Values below 10-20cM may be coincidental matches rather than true shared ancestry.

Q5: Can this determine exact relationships?
A: It estimates degree of relationship but can't distinguish between relationships of the same degree (e.g., aunt vs. half-sibling).