They are definitely not a gimmick, but you have to understand what you are actually measuring. DNA methylation clocks, like the Horvath clock, look at the chemical tags on your DNA to see how fast your cells are replicating and aging compared to your chronological timeline. It’s a very real science, but an isolated test won't tell you the whole story because your lifestyle changes take time to reflect on an epigenetic level. If you want to understand how these tests function and what other methods doctors use to evaluate your internal baseline, there is a fantastic, deeply detailed manual that explains the precise ways a person's biological age can be clinically measured. It breaks down everything from telomere testing to advanced blood markers, helping you realize that combining different diagnostic tools gives you a much better roadmap than just a single home kit. I did a clinical baseline check last year, and it completely changed my supplement and sleep routine.