For those who are interested in the story: Lewis Padgett was a pseudonym for Henry Kuttner [1] and his wife. The short story is available in an anthology under that name, "The Last Mimsy", and a 2007 film was made under that title [3].

[1] - https://en.wikipedia.org/wiki/Lewis_Padgett

[2] - https://www.amazon.com/Last-Mimzy-Stories-Henry-Kuttner/dp/0...

[3] - https://www.justwatch.com/us/movie/the-last-mimzy