Although it has been widely reported that there is considerable variability in in vitro CFTR‐mediated responses among epithelial cultures generated from CF patients, even across those harboring the same mutations (Van Goor et al, 2011; Awatade et al, 2015; Dekkers et al, 2015), we were surprised to observe the extent of large variability among the four non‐CF family members. The gene discussed is CFTR; the disease is cystic fibrosis.