To isolate genetic value, genetic values should be expressed as deviations from what?

To isolate genetic value, genetic values should be expressed as deviations from what?

• A. The environmental mean
• B. The population mean
• C. The mean of the additive values
• D. The group mean

Answer: (D)

Expressing genetic values as deviations from the group mean lets you separate genetic merit from environmental influences. In a group with a similar environment, the average performance—the group mean—captures both genetic and environmental effects shared by that group. When you look at how an individual differs from that group average, you isolate the portion due to its own genetics—the genetic deviation from the baseline. If you used an environmental mean or a different baseline, environmental differences across groups would be embedded in the reference, making it harder to attribute the remaining difference to genetics. The mean of additive values isn’t a suitable baseline for this purpose. So the appropriate reference is the group mean.

Expressing genetic values as deviations from the group mean lets you separate genetic merit from environmental influences. In a group with a similar environment, the average performance—the group mean—captures both genetic and environmental effects shared by that group. When you look at how an individual differs from that group average, you isolate the portion due to its own genetics—the genetic deviation from the baseline. If you used an environmental mean or a different baseline, environmental differences across groups would be embedded in the reference, making it harder to attribute the remaining difference to genetics. The mean of additive values isn’t a suitable baseline for this purpose. So the appropriate reference is the group mean.