At what point can a child have their own opinion without it being seen as backtalking?

I think this would be an unstable household. If I disagree on something and tried voicing my own opinion in a civilized manner, it was seen as backtalking already. So basically I had to agree to everything they did or said, even on something I really believe was unfair, not right.

For instance, I didn't like the way my parents once treated a Mexican maid. They treated her badly for that reason. They're straight forward racists but I was just 10 and had to keep my mouth shut.

I can understand a spoiled brat that gives their parents attitude and screaming after being kindly asked to help around the house. That wasn't the case with me.

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I felt as if I didn't have any voice as a kid nor during my early-mid teen years. Even a kind, disagreement (just for the reason I'm already disagreeing with them) was considered me challenging them and backtalking.
At what point can a child have their own opinion without it being seen as backtalking?
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