How old am I really? These tests measured my biological age

How old am I, really? I spit into a tube, rubbed the inside of my cheek, and pricked my finger to find out.

I mailed my samples to three companies who promised to give me my “biological age” based on chemical changes to my DNA. The results, according to the companies, would not be based on the date of my birth, but on the aging of my cells and my organs.