And these mutations aren’t dominant alleles, because they arise from reduced pigment production, reduced function in pigment receptors, or other interference with the pathways that turn most people’s red hair color dark. This means that getting an allele with the “normal” function will reduce or remove the effects of the allele that causes blonde or red hair.
The mutation is a single amino acid change in the red hair color. It is likely that the mutation destabilizes the protein, causing it to unfold and remove the pigment that the gene normally produces, causing blondness. This is inferred through the presence of an analogous mutation in mice in the same gene that causes light brown fur instead of brown fur. The mutation is recessive, meaning that both copies of the gene need to be mutated in order for the person to be blonde.
If you’re not choosing a color that is meant to have lift, or to lighten red hair color, it won’t lift. If it doesn’t lift, it will just deposit color on top of color. Think of the two colors as crayons, what happens when you use light red crayon over dark red crayon?
I’m going to assume that the darkred hair color is an artificial hair color and if that is indeed the case it will not get lighter by simply applying a lighter color. Think of putting brown marker over top of black marker…. No difference right. That is because color does not lift color. Bleach must be used to lighten the darker color first. I would strongly advice going to a professional for this.