The photo page of the January 3 1933 edition of the Toronto Daily Star turned out to be a good source of material. Here’s a photo from that page of a family of swimmers from Milwaukee:
I did searches for Ruth Dierolf and Edward Dierolf and didn’t find anything, which suggests that the junior Dierolfs did not go on to noteworthy swimming careers.
I did find that an Edward D. Dierolf wrote a book in 1915 titled Swimming: Be Your Own Instructor. I strongly suspect that this was the man shown here as Pa Dierolf, but I have no way of knowing for certain. The Amazon link for the book contains the following excerpt from it:
Right here lies the starting point for them to gain that wonderful confidence, which in later years will prove that the child is as safe in the water as it is on land. Usually the mother becomes frightened and does not know what to do. She takes the babe out of the bath, pats it on the back and some times even tries to shake the little body, hoping that by so doing the water will come out of the nostrils.
I’m confused. Is the mother dunking her child into the bathtub?