tl;dr The individual researcher typically is, but science as a community of peers isn’t. (For caveats see bottom of post.) This post was inspired by a social media post by Prem Devanbu.
Individual scientists naturally have opinions, ambitions, and hopes, and this influences the research questions they chase and the hypotheses they frame. Despite many safeguards in research methods, results of individual studies may very well be influenced by these beliefs. Medawar  explains this nicely in a BBC interview in which he argues that science isn’t a logical deductive endeavor from start to finish, but that it usually (always?) starts with a researcher’s intuition. As a consequence, early results may well be biased. Science is a human endeavor.
But then there are other scientists, and a lot of them if the topic is of broad interest. They will try to repeat (replicate) the research and over time will correct any biases in the work. The most famous example I’m aware of is the Millikan experiment  of measuring an electron’s charge. The original measurement by Millikan was way off, and replications of the experiment were anchored by the original values. Over time, however, the kinks were worked out and the measurements approached what we today believe is the correct value. Science is still a human endeavor.
All of this is to say that science is a social system, but it self-corrects over time. Of course, time is relative, and can take quite a while. Scientists are educated by other scientists, and some biases can run so deep that whole communities may be biased. It will require a whole paradigm shift to shed those biases. However, these paradigm shifts happen regularly, even if sometimes in lengthy intervals only .
 Medawar, P. B. (1964). Is the scientiﬁc paper a fraud? BBC Publications.
 Kuhn, T. S. (1962). The structure of scientific revolutions. University of Chicago press.