Should the doctor in your family be involved in your care?

I am constantly hearing from many sources that doctors shouldn't treat their own family members and friends when asked to do so. Can anyone provide data or evidence for this? I see "ethical" guidelines about this from state licensure boards, and medical societies. My malpractice insurer says it increases risk too. My two cents: I am aware of absolutely no evidence for these "ethical" guidelines. I'd like to see a single study of this question worth anything or any date, from a malpractice insurer or otherwise, showing that worse outcomes occur when trusted family member physicians, whom a patient wishes to be involved, are involved in a patient's care.

Here's a call to action for all my former academic colleagues at Johns Hopkins, UCSF, etc. How about some evidence-based patient-centered care? Why not do a study of whether people treated by family members, or whose family member physicians are involved in their care, have better or worse outcomes? As a profession, why do we assert something we have absolutely no evidence for besides our own prejudices? For those of you who do have a good clinician in your family whom you trust, wouldn't you consult them when you're ill?

In our practice, we assert in our tag line that "everyone needs a doctor in the family" (www.myadvicedr.com). We believe that on average, people benefit from having someone they trust, who is accessible, involved in helping them choose providers, compare treatments, and help them make sure that planned procedures or treatment are really the best thing for them.
It is my aim to be just like the doctor in the family whom you trust would be. So I definitely believe that trusted doctors in the family are a big help.

I'm willing to be proven wrong, but show me the data!! I would assert that we should not make blanket assertions without evidence as we are doing now in our state boards, medical societies, and malpractice insurance companies. How about some effectiveness research?

And meanwhile, I will continue advise my patients and others: If you have a trusted physician in your family, by all means continue to call them up and ask their opinion about everything you can. Until I see the evidence, I'm going with my gut. And if you can show me some evidence, I'll promptly post it the next time I blog.