My granddad stuttered as a child, my grandparents had 2 boys & 2 girls and one girl and one boy (my dad) stuttered until teenagers. Out of 10 of his grandkids I’m the only one who ever stuttered & I haven’t grown out of it like my dad aunt and granddad did. My aunt that stuttered as a child hasn’t got children though so i don’t know if her kids would’ve stuttered too as she did, but yeah in my family it definitely comes from through the male side and has been passed on through males. I’m female btw