What do the genetics have to be in order to be born with red hair?

I think it’s recessive which would mean the father would also have to be a red-hair-gene carrier. But my understanding of genetics is a gross oversimplification…

Hair color is controlled by multiple snps so it takes more than one gene set to determine hair color. It’s not easy to predict even with genetics. It does not exclusively come from one side or another. It’s quite random but the more “red hair” genes you have the higher the probability. My sisters have bright red hair and blue eyes. I have jet black hair and brown eyes. My 23 and me profile predicted blonde hair and blue eyes for me. Both parents have brown hair, one with blue eyes and one with brown. None of my grandparents had red hair or even black hair. They were all blonde or brown haired.

Red hair requires recessive genes from both parents, same as eye color. But hair has a spectrum of color, which can influence the lightness or darkness. For red hair, all the factors have to line up just so.

Here’s an explanation for the layman.

I have a red headed daughter. I was so glad when she married a redhead (I think I raise narsissist children) because it insured I would have redheads grand babies. I got 4 :-)

Both parents have to have the red gene.