The coefficient of relatedness between two brothers is __________.

• A. 0.75
• B. 0.25
• C. less than the coefficient of relatedness between father and son
• D. 1.5
• E. the same as the coefficient of relatedness between mother and daughter

Answer: (E)

Verified step by step guidance

1. Understand the concept of coefficient of relatedness, which measures the probability that two individuals share a particular gene inherited from a common ancestor.
2. Recall that the coefficient of relatedness between parent and offspring (e.g., mother and daughter or father and son) is 0.5, as the offspring inherits half of its genes from each parent.
3. Recognize that siblings, such as two brothers, share genes from both parents. Each brother inherits 50% of their genes from each parent, but the specific genes inherited can vary.
4. Calculate the coefficient of relatedness between siblings. Since each sibling has a 50% chance of inheriting any particular gene from a parent, the probability that both siblings inherit the same gene from a parent is 0.5 * 0.5 = 0.25. Since there are two parents, the total coefficient of relatedness is 0.25 + 0.25 = 0.5.
5. Conclude that the coefficient of relatedness between two brothers is 0.5, which is the same as the coefficient of relatedness between mother and daughter.