This article is pretty useless and doesn't give any insight into the current scientific understanding of stuttering genetics. A lot of early genetics info came from studying families with many people who stutter. By comparing these individuals who share a trait and much of their DNA sequence against the broader population who does not, we've identified a number of genes that, when mutated, confer a high risk of stuttering. Another method is called GWAS, where you basically look at the genomes of lots of people with a trait and compare them to lots of people without. It's harder than if you're looking at just one high-risk family, but you also have the chance to identify lots of mutations that each contribute maybe a smaller risk individually but may not show up in your high-risk families. Similarly, you get a list of mutations that confer risk for the trait. [Here is one such recent study](https://www.sciencedirect.com/science/article/pii/S2666247721000543). If you're interested, Table 2 is the list of mutations they find. It doesn't mean much on its own, but that's the kind of result we get-- "these genes may play a role possibly?" Also check out the Introduction section. There is lots of good summarizing info on all this and more in there. Here's [another study](https://www.sciencedirect.com/science/article/abs/pii/S002199241830162X) that looked at the response to speech therapy, and found some of these high-risk mutations correlated with poorer response to therapy. The next question is: what is it about these genes that causes (or contributes to, or increases risk of) stuttering? Some analyses have pointed towards the [dysfunction of lysosomes](https://www.sciencedirect.com/science/article/pii/S0301008219303363) (reach back into your grade school biology, here; those are the organelles that clean up the trash & waste building up in your cells) in neural cells as a molecular/cellular mechanism. Lots more needs to be done in this area, though. The next *next* question is: what can we do about it? Answering that still seems to be a long, long ways off, yet.