I just wanted to clarify that the online Predictive Index test is a personality test administered by an outside source. Answers given are kept confidential and are not shared back with HR or anyone at the company. The Predictive Index test asks your age because studies show people answer the questions differently based upon various generational factors. For example, being punctual. and on time to someone in their 50-60s means to get to a meeting about 5 minutes before so there before the meeting start time. But for someone in their 20-30s, if they arrive by 5 minutes after the meeting start time, they still feel they were punctual.
Personality tests, such as these, all ask for age or date of birth. Because the information is kept from the company, there's no way it could be used to determine if a person would hired. So it is not an illegal question for the personality test company to ask.