In my experience you teach the first child manners.
You teach them how to sign please before they can speak it. By the time they talk they ask for things with complete sentences and when they tell stories, (so many stories) it is done in a fairly normal, if excited, speaking voice.
The second child you try. But the first child is “helping” by making up pretend signs that change minute to minute so the sign language thing never really catches on. And your hands are so full with the first child’s polite, but attention seeking stories, that so long as the second child says what they want instead of sitting and wailing until you figure it out, you no longer care exactly how the information is presented.
As the first child continues to jabber on night and day, the second continues with her demands and the third is left with only one option -loud.
Polite, but loud.
Full sentences, at top volume.
Stories, just as many stories as that first child, but louder ones.
Songs, all sung at top volume.
(Yes, I know the video is sideways, please tell me if you know how to fix it!)
And you try, you really try to pay attention to them when they ask for something the first time, when it might be in a nice normal voice. But, you are the mother of three and, inevitably, you miss it. The over shadowed and ignored third child defaults back to loud and you finally respond. The behavior is rewarded, you sigh because you know what you just contributed to, again, and the third child continues to be loud.
Happy – but loud.
Yes, in my experience, the third one is the loud one.