Diane Keaton, an American actress and director, is known for her signature style of wearing turtlenecks. Turtlenecks, also known as roll necks or polo necks, are a type of sweater with a high, round neck that covers the neck and extends up to the chin.

Keaton has been wearing turtlenecks for many years and has incorporated them into her personal style and fashion choices. She has been photographed wearing turtlenecks on numerous occasions, both on and off the red carpet.

There are several possible reasons why Keaton may choose to wear turtlenecks:

1. Comfort: Turtlenecks can be comfortable and cozy, especially in colder weather. Keaton may prefer the comfort and warmth of a turtleneck sweater.
2. Practicality: Turtlenecks may be a practical choice for Keaton, as they can be worn on their own or layered under other clothing.
3. Personal preference: Keaton may simply enjoy the look and feel of turtlenecks and have chosen to incorporate them into her personal style.

In addition to turtlenecks, Keaton is known for her signature style of wearing oversized glasses, tailored pants, and other classic pieces. She has been described as having a timeless and chic sense of style, and her fashion choices often reflect her personal taste and preferences.

It is worth noting that celebrities and public figures often have stylists and fashion advisors who help them choose their clothing and create their personal style. It is possible that Keaton’s choice to wear turtlenecks may be influenced by these professionals as well.