In people who have red hair, the skin cells (melanocytes) that produce pigment have a variant receptor on the cell surface. When exposed to UV light, this variant fails to trigger a switch that ...

Joanna Scutts is a freelance writer and board member of the National Book Critics Circle. Red By Jacky Colliss Harvey Black Dog & Leventhal. 230 pp. $28 Is red hair a blessing or a curse? To ...