Everyone is indoctrinated -- we are all given a foundation and framework just from being born into a certain culture, a certain body, a certain time period. It limits the information we are given. So I don't fault anyone for what they're born into it, we all have a starting point in life.
BUT
we're responsible for examining what we've been given, testing it, learning from it, stretching it, pulling at it, determining whether or not it seems to make sense and is true, whether it leads to things that seem harmful or hurtful (although again, our definitions of such sometimes are affected by our culture), and so forth.
Just for personal examples: I was raised to believe in a particular religious faith, and i had no access to information to challenge that world view based on the location and time period. I disregarded some of the teachings based on what I saw as making little sense but otherwise accepted the stuff that made sense at the time. However, when I left that area and was exposed to other others as a young adult, then I found my views starting to change. It came from a drive to make sure that what I believed made as coherent a picture as I could formulate in life. So my views continue to change even a few decades later. I don't consider myself in a "fixed" state of being, even if at this point I believe a lot has settled out and what I believe now is in some ways very different from what I believed when I was 15. To me, that is taking responsibility for my own values and beliefs rather than just running with my indoctrination / starting point in life.
What is interesting to me is that you just need some kind of value system to expose the deficiencies in the worldview you are given. For me, my litmus test was rationality. For my mother (who seriously is one of the least cerebral people I know, and I'm not being condescending, it's just not how she operates), her value system is her sense of suffering in the world and who is being hurt. She was raised steeped in the same religious value system, but I've seen her quietly challenge the things she was being told because what was being promoted were things that hurt people she loved. So her values involved being true to people she cared about and wanting to alleviate suffering, versus voting a certain way or promoting particular religious values that caused pain. It took me some time to grasp that about her but in her own way she has also challenged her own upbringing and taken responsibility for her beliefs.
Anyway: I can see "indoctrination" as a reason, but I don't necessarily see it as an "excuse" especially if there are notable crux points where someone was in a position and even inclined to challenge their own views but just took the easy way out by embracing the familiar out of convenience or self-indulgence. I would be especially leery when the price to be paid for one's beliefs and convenience must be paid by OTHERS; I think one has to be paying the price oneself for whatever values one has.
