get paid less: If this were true, there would be a lot of lawsuits out there. What I think he must have meant was that many D.O.'s go into primary care, and primary care doctors get paid less than physicians that specialize. D.O.'s are not limited to primary care medicine.
get less respect: We all earn our respect. Stereotypes only get people to initial impressions.
don't get promoted as well: the AOA has not promoted D.O.'s as much throughout history. Recently, there have been advertisements in several magazines about D.O.s, but most people still don't know the difference between a D.O. and an M.D. I think the real issue is, will this really affect your practice? Will someone in need of medical care really care whether you are a D.O. or an M.D. if you are delivering quality health care? Insurance companies aren't going to discriminate against D.O.'s. I firmly believe the quality of your care will improve as a D.O., because of the approach to medicine. The name of the medical school is not important unless you are going into academic medicine. Your residency is more important.
recognized as "second class doctors:" Recognition based on stereotypes does not equal recognition after being treated. Each individual doctor gets recognized for how he does his job. Colleagues may have doubts, but each year as the new residents get started, you are judged by how you perform, your in-service exams, etc.
This D.O. vs. M.D. war is sad, because it discourages a lot of potentially good pre-meds from discovering more than the stereotypes. I understand the importance of pleasing your father, and I don't mean to minimize your problem. As a female, I am certain there will be someone out there who will treat me different than a male because of stereotypes. I felt that osteopaths were "inferior" initially. Yet I understand so much more about the value of osteopathic medicine after I began my training, and I similarly had to overcome many negative stereotypes put out there by pre-med advisors. Good luck.