When X-Chromo was very first learning to talk, we discovered something interesting. We played the standard game with her: point at something and ask her, “What’s that?” or at a person and ask, “Who’s that?” The latter was quite common at the dinner table every night.
I would point at my husband. “Who’s that?”
“Dada.”
He would point at me. “Who’s that?”
“Mama.”
One of us would point at her older brother. “Who’s that?”
“Hmph.”
Y-Chromo’s given name is nowhere near “Hmph” in sound. Neither were his many nicknames. But night after night, she would respond: “Dada, Mama, Hmph.”
If you look up the definition of “hmph” you’ll see that the sound indicates annoyance or indignation. Traits that set the tone of their relationship for next several years.