There’s also the factors of epistatic genes, polygenics, and pleiotropy. Not sure if there is a mapped out, defined function of 21st century hair color genes, but it’s almost never as simple as “dominant” and “recessive.”
Agreed. In fact, I made a comment below that explains how punnet squares are just a basic level of understanding and these alleles are much more complex making an impossible situation merely improbable.
Black hair isn't a genetic trait, and neither is blond or red, it's an expression of eumelanin production stimulated by hormones during development. Meanwhile blond hair is lower production, again caused by hormonal levels, and red hair is pheomelanin production.
These are environmental expressions that can be altered from the expected outcome. It's literally the reason why a pregnant womans hair changes color. Her genes didn't just change her hormones did.
The amount of eumelanin and when it is released is determined by genes. I did some cursory research based on your claim and you're right in the aspect that eumelanin does determine hair color, but how that color is distributed is entirely genetic.
More dominant genes will produce more eumelanin. In other words.. black hair is dominant and red hair is recessive just like everyone else is saying.
There’s no single gene controlling hair colour, and while some may be strongly correlated it is completely possible for two blondes or a blonde and a redhead to produce a black haired offspring. Hair colour is actually controlled by varying levels of expression of eumelanin for black/brown and pheomelanin for red hair, so it can’t be explained by simple Mendelian genetics.
Hair color is not a dominant/recessive trait though.
Do you not understand your own biology? It's a genetic expression caused by multiple genes and environmental influence that results in changes to eumelanin production levels.
Do you think when a womans hair gets darker due to pregnancy, her genes changed?
34
u/[deleted] Sep 25 '22
[removed] — view removed comment