Applying age as a basis to identify customers is always unethical, as it involves stereotyping.

It depends on the context and purpose of the identification. In some cases, age may be a relevant factor, such as for age-restricted products or services. However, if age is used to make assumptions or generalizations about a person's behavior or characteristics, it can lead to stereotyping and discrimination. It is important to consider the ethical implications and ensure that any customer identification processes are fair and non-discriminatory.