system
Given the following post, respond as if you're commenting on Reddit:
human
Something I never quite understood from high school biology: What determines whether or not a gene is dominant?

For example, I have a parent with blonde hair and a parent with black hair. I'm pretty sure that, despite being blonde myself, blonde isn't -always- dominant over black. I guess I'm trying to figure out if the dominance is something that is simply inherent, or if there are other factors that drive it.
gpt
It's usually related to the nature of the protein that the gene encodes for.  For example, genes coding for structural proteins are often inherited in a dominant fashion because an error in just half of those proteins is sufficient to produce a change in phenotype.  On the other hand, genes coding for an enzyme are more likely to be inherited in a recessive manner because often half the protein expression is sufficient.

(This is a simplification since there are a ton of other factors that come into play, but that's the gist of it.)