DNA test kits aren't a scam, but you need to know their limitations and realise that they’re actually a spin-off of much broader ambitions. For example, researchers are using anonymised DNA test results to create maps of human migration patterns, but also to develop personalized and population-based healthcare, partly by identifying people at risk from genetic conditions. For population-genetic modelling the growth of DNA test kits is great news.
However, what DNA test kits don’t do is give simple, quick and 100% reliable information about where a specific individual’s ancestors came from. So if you’re researching your family tree, by all means get a DNA test kit and feed the results into your own research. But if you’re only after a quick DNA-based sense of identity – confirmation of your own unique heritage and ancestral roots – DNA test kits are not going to give you enough accuracy for that.