You're certainly correct that medicine, as such, lies at the interface of biology and social science. Even biology itself, exclusive of medicine, can be greatly affected by sociology. There is a great book on the topic called The Mismeasure of Man by Stephen J. Gould in which he recounts the vast undertaking in the late 19th c to "prove" the superiority (defined arbitrarily, of course) of whiteness. This was at a time when blacks were suddenly free and many immigrants from parts of Europe other than Britain, Germany, France and Scandinavia were suddenly entering the US in great numbers, especially Jews from Eastern Europe.

In response "Science," led by the Swiss-American head of zoology at Harvard, Louis Agassiz, "proved" that there was a racial hierarchy to man, with (to no one's surprise) Britons and Germans being at the top, followed by the various groups all the way down to blacks and Native Americans, the inferiority of whom closely correlated with the relative darkness of skin. This work was the "scientific" basis of immigration quotas, and eventually was used as a founding principle of eugenics (which of course helped justify the Holocaust). So no, biology is of course not immune to social leanings, and of course medicine, which is part biology and part sociology, is even more prone.

Edit: As scientists, I think the best we can do is recognize that we're not input/output machines. I don't know if we can do any better than that, but I do spend a hell of a lot of time thinking about it, which I hope is a good start.