My sibling stutters

My sibling stutters My little sister (6F) stutters the beginning of her sentences and a little of the middle. For example she’ll say " I-I-I like ice cream " she doesn’t do this all the time. I can’t tell if it’s baby talk or not. Her grandma babies her a lot and talks to her in a baby voice. I can’t tell if it’s a real stutter or not because I’ll tell her to slow down and to not talk like that and she’ll stop talking like that. I also notice she usually stutters more when talking to an adult.