Of course, “should not treat” is a recommendation, not a rule, and it seems to safe to say that situations exist in which it can be ignored. It’s likely fine for the doctor in your family to fill your cavity or administer a flu shot; it’s too risky for a parent to perform a craniectomy on their child or a spouse to come up with a cancer treatment plan for their partner. But things get murky when you move into plastic surgery territory.

The most popular procedures carry the potential for serious risks and complications, and personal feelings surely come into play when permanently augmenting the face and body of a loved one; yet according to one study by the Journal of the American Society of Plastic Surgeons, more than 80% of plastic surgeons say they would—and have—performed elective cosmetic surgery on spouses or other family members.