I think wisdom is multi dimensional. It can come from personal experiences, personal insights gleaned from what a person has been. For some it can come from the application of knowledge or from having done something once, maybe failed at it and tried again, wiser and stronger from the experience. I think there's also the notion that some people are born wise. Not perhaps that they are born with all the knowledge needed to be wise but that they have disposition to be wise, and take life experiences on board and grow in that nature. Wisdom is likely also multi faceted in a person could be wise in some areas but not in others. I agree that some of wisdom probably does come with age due to the amount of life experience a person will have had. However some of the wisest people I've met haven't been 90, but instead were just people who were likely blessed the ability to absorb all experiences and take the learning from them, and absorb the wisdom of others and this has made them 'wise before their time'.