The article by Kesselheim et al1 regarding the ethics of hematopoietic stem cell (HSC) donation by biological siblings of adopted children points out the importance of intimacy in justifying minors participating as HSC donors. However, the article highlights one common error in this process. Because HLA testing is a simple blood test, parents and physicians believe that they can test children, and do so without considering its broader implications. While the physical risk is minimal, if the child is found to be HLA identical to the potential recipient, questions arise about whether the child is an appropriate HSC donor. This question, however, should be asked before HLA testing is done. In that vein, the case cited by Kesselheim et al was problematic despite the fact that the siblings were found to be non–HLA compatible: nonintimate siblings should not be evaluated to determine if they are eligible to serve as HSC donors.2