Robin Corporation is owned as follows:

Isabelle ........................................................26%
Peter, Isabelle's husband ..........................19%
Sonya, Isabelle's mother ...........................15%
Reggie, Isabelle's father ............................25%
Quinn, an unrelated party ........................15%

Robin is on the accrual basis, and Isabelle and Peter are on the cash basis. Isabelle and Peter each loaned Robin Corporation $40,000 out of their separate funds. On December 31, 2018, Robin accrued interest at 7% on both loans. The interest was paid on February’ 4, 2019. What is the tax treatment of this interest expense/income to Isabelle, Peter, and Robin?