John McWhorter in The Atlantic:
Is there anything inherently “doggy” about the word “dog”? Obviously not—to the French, a dog is a chien, to Russians a sobaka, to Mandarin Chinese-speakers a gǒu. These words have nothing in common, and none seem any more connected to the canine essence than any other. One runs up against that wall with pretty much any word.
Except some. The word for “mother” seems often either to be mama or have a nasal sound similar to m, like nana. The word for “father” seems often either to be papa or have a sound similar to p, like b, in it—such that you get something likebaba. The word for “dad” may also have either d or t, which is a variation on saying d, just as p is on b. People say mama or nana, and then papa, baba, dada, ortata, worldwide.
Anyone who happens to know their way around a lot of languages can barely help noticing this eerie similarity. But when it comes to European languages closely related to English, like the Romance and Germanic ones, this isn’t so surprising. After all, these languages are children of what was once one language, which linguists call Proto-Indo-European and was likely spoken on the steppes of what is now Ukraine several millennia ago. So if French has maman and papa, and Italian has mamma and babbo, and Norwegian hasmamma and papa, then maybe that’s just a family matter.