Some research has shown that children who stutter have higher levels of testosterone then children who don’t stutter. So it has been proposed that there’s a hormonal component involved in stuttering, which is contributing to the differences in the ratio between males and females. This can also be why some children have an onset of stuttering after puberty. Here’s the study i’m referring to: [https://pmc.ncbi.nlm.nih.gov/articles/PMC4437599/](https://pmc.ncbi.nlm.nih.gov/articles/PMC4437599/)