I have red hair! Do you know if that is rare?
I don't personally know how rare it is, but it seems like it isn't very common. I don't often see people with red hair!
My son has a red hair tint but it is mostly brown.
I think that is pretty common. Do you have extremely red hair or is it more towards the blonde or brunette spectrum? 
It used to be strawberry blonde and is now more brown.
Red hair
Red hair (or ginger hair) occurs naturally in one to two percent of the human population, appearing with greater frequency (two to six percent) among people of Northern or Northwestern European ancestry and lesser frequency in other populations. It is most common in individuals homozygous for a recessive allele on chromosome 16 that produces an altered version of the MC1R protein.
Red hair varies in hue from a deep burgundy or bright copper (auburn) to burnt orange or red-orange to and strawberry blond. Characterized
gingers, like the ones Cartman starts associating with, and "daywalkers", people like Kyle with red hair but no freckles or light skin.
In the episode, a man tells Stan and Kyle "If you really don't want to have ginger kids, marry an Asian woman. Asians don't carry the recessive gene. I know a guy who's marrying a Japanese woman very soon for just that reason." This is an intentional reference to Parker doing the same thing in real life. He once had