I used to have brown hair. My driver's license shows me with a shoulder length brown wig and says my hair color is brown. I need to renew my U.S. passport and the application asks for hair color. I plan to wear a blonde wig for the photo, and assume I will put "blonde" as my hair color. But the hair on my head now is pure white, so presumably my "natural" color is now white. It seems a little crazy to be brown, blonde and white at the same time, but if I were to take an international airplane flight, I would almost certainly wear a scarf and not brown or blonde hair. OK, perhaps this is more of a vent than a plea for new information, since I don't think there is any. I don't want a photo of my crazy "natural" hair, and I don't want to attract attention by saying my hair color is different from what the photo shows. So much for hoping my hair would grow back before my passport expired! Thanks for listening.
I put bald/black on mine, I just renewed my passport and notice that hair color is not even listed on the passport itself, but it is probably in their files. I would wear the color that you most likely wear on a day to day basis. If you travel with a scarf, I doubt they would ask a lot of questions, they are aware of cancer and possibly alopecia as well. In addition people change their hair color all the time.