Looking at your comment I am not sure we disagree. Rather than unpacking what I'm trying to get at (which is orthogonal to the discussion), I'll leave it be. But if you are curious look up "heritabitility" in Hartl & Clark, they explain the issues more lucidly than I could here.
Link.
"Razib Khan has an academic background in the biological sciences, and has worked for many years in software. He is an Unz Foundation Junior Fellow. He lives in the western United States."
Razib's writings can be found on his blog, Gene Expression.