In fact, if you look at people within our government, they seem to be quite enthusiastically fighting the war against their own people at the behest of the United States. So it doesn't seem to me that the strong way to oppose this is by joining politics at all, but just to keep speaking and to keep talking about it.
Spouses have each other, and even when one eventually dies, they have memories of a time when they existed before that other person and can more readily imagine a life without them. Likewise, parents may have other children to be concerned with--a future to protect for them. To lose a sibling is to lose the one person with whom one shares a lifelong bond that is meant to continue on into the future.