Actually this may not be true in cases of familial stuttering: >"Another interesting finding is that the male-to-female ratio in familial cases of stuttering is approximately 1.5:1. This means that in families who appear to have some genetic transmission of stuttering, for every 1.5 cases of males who stutter, there is a case of a female who stutters. This figure is considerably different from past reports of male-to-female ratios for stuttering, which have previously been described as 4 or 5 males for every 1 female. This suggests that genetic transmission of stuttering affects females almost as frequently as males, and that the male-to-female ratio is much higher, probably 7 or 8 males for every 1 female, for individuals with no family history of stuttering." https://www.stutteringhelp.org/genetic-and-neurological-factors-stuttering That said, these don't speak to the chances of anyone in the family actually having a stutter. There is a strong familial line of stuttering in my family, and even then most either never stuttered or grew out of it during childhood.