Ah, birthdate makes much more sense. My confusion stemmed from misreading the comment as "using these properties: [given age](?), [gender], [zip code]" instead

Ah, birthdate makes much more sense. My confusion stemmed from misreading the comment as "using these properties: [given age](?), [gender], [zip code]" instead of "given these properties: [age], [gender], [zip code]".