you answered the question yourself.
The AMA Code of Medical Ethics' opinion on physicians treating family members.
journalofethics.ama-assn.org
here are a few of the inherent risks that i foresee:
1. increased testing "to make sure everything is okay", including unnecessary testing
2. increased utilization of treatment such as antibiotics and medications
3. difficulty in maintaining a scientific nonbiased view of the patient and symptoms
4. difficulty in assessing effectiveness or lack thereof of treatment.
5. patient trust that might be unfounded or not understand that the aforementioned bias has occurred.
6. as a whole, unless you establish a true doctor-patient relationship, poorer monitoring and documentation of medical history.
i would also worry that the family member - if not an immediate family member - would hold resentment or tear at the family dynamics if things did not go as planned.
Straight from AMA, "It would not always be inappropriate to undertake self-treatment or treatment of immediate family members. In emergency settings or isolated settings where there is no other qualified physician available, physicians should not hesitate to treat themselves or family members until another physician becomes available".
what you stated above just proves one point, you don't know how to remain objective when treating friends/family members. The key is to remain objective, then all your presumption (or shall I say "prejudice") makes no sense.
You should treat all your patients the same, not group them to friends, family members, class 1 patients, class 2 patients, etc. Your training should have taught you.
Sure, you can have concern your family members hold you resentment, so you can decide not to treat them. It's your prerogative to do so. But don't say because you don't want treat your members/friends or you believe you might not be objective, then you would label other physicians who do, as "unethical".
Have you ever been involved in your family members' healthcare? Have you ever taken your mom or your dad to a doctor's office? Have you ever been an advocate for your parents, spouse? If you haven't, you are lucky. Some of us don't have the luxury because we see the quality of healthcare in this country is going down the drain. Like I said before, who can take care of your loved ones better than yourself, if no good alternatives available?
Lastly, if you have the same mindset, let me ask you this question, who will be taking care of YOU when you are sick? because after all, you, as a physician can be biased when seeking healthcare. Another doctor/colleague of yours can refuse service to you for the same reason, because s/he can say it's impossible to remain "objective" because you guys know each professional or personally. Stupid argument, don't you agree? All in the name of remaining "objective".
Be careful of what you wish for. Treat others like how you'd wish to be treated.