We've gone through this many times, its nothing nefarious.
1) doctor uploads his contacts (phone number/email addresses) to facebook and sets his contact info
2) you upload your contacts and set your contact info
if there's one match between them, facebook believes (correctly) that there is some sort of existing relationship between you. The fact that its professional and not personal and you want facebook to just be personal doesn't change it.
In other cases facebook can see you are friends with many of them same people and hence figures you might know each other.
1) doctor uploads his contacts (phone number/email addresses) to facebook and sets his contact info
2) you upload your contacts and set your contact info
if there's one match between them, facebook believes (correctly) that there is some sort of existing relationship between you. The fact that its professional and not personal and you want facebook to just be personal doesn't change it.
In other cases facebook can see you are friends with many of them same people and hence figures you might know each other.