A coincidence or not?

[bannork]

Listening to a niece calling her parents, I wondered if it was a coincidence both words mum แม่ and dad พ่อ are falling tones, in English when we call from far away, our tone falls, 'Hey... John' perhaps it's a natural thing universally.

On another note, in many languages the word for mother begin with m as the baby has few teeth, so seeing the most important person in his/her life they utter ม mmmm, or in the case of my grandson ว แวแวแวแว !