The practice of hair curling has been around since nearly the beginning of recorded history. People with straight or slightly wavy hair have a variety of options available to turn their tresses into sleek curls. The techniques are all only temporary, however, as the genetics behind hair texture are difficult to change.
Your genes determine whether you'll have straight or curly hair. People with two copies of the curly hair gene have hair follicles that are slightly bent on one side, meaning that the hair grows in a sort of corkscrew fashion. People with only one copy of the gene have a few hairs growing this way and others growing straight. And people with no copies have no curling hairs. Curling hair has long been associated with femininity and romance. It's common for women to curl their hair for special occasions such as weddings, parties and romantic dinners.
Hair can be curled on a very temporary basis with curling irons or hair curlers. These methods work with heat. A strand of hair is wrapped around a warm element, and the hairs are crimped by the contact with the heat. For people looking for more lasting curls, chemicals can be applied to chemically change the structure of the hair into a crimped, curled texture. While this method can last for weeks or longer, since the hair's structure itself is chemically changed, it doesn't last forever. Hair follicles are constantly at work, pushing older hair from the scalp to the tips. The new hair that comes in will still be the original texture of the hair. At present, there's no way to genetically engineer your hair to move from straight to curly. There are people, however, who report hair texture changes during puberty, menopause or other times when hormones flood the body. This may provide clues for scientists to use to develop hair-curling drugs in the coming decades.