This isn't GxE heritability (i.e. genetics vs. environment), but rather a metric for how SNPs influence additive traits. It's best considered a lower bound to what we would normally consider heritability.
In this case, it's not an additive, multi-factorial trait; it's epistatic. There's a 'black hair' gene that overrides whatever else is happening in your genome. This is often the case with color traits: a dark color overrides anything lighter. It's the classic example of dominance.
In this case, it's not an additive, multi-factorial trait; it's epistatic. There's a 'black hair' gene that overrides whatever else is happening in your genome. This is often the case with color traits: a dark color overrides anything lighter. It's the classic example of dominance.