@amszmidt @ksaj @loke I was also thinking of how "grandchild" is "barnbarn", and "grandson" is "sonson" or "dotterson", so in this case Swedish has both the specific and unspecific words. But I feel the preference would usually be "barnbarn".
By the way, also fun to note that in Northern England and Scotland they have the word "bairn" for child/barn. Old Norse influence?