I kinda feel it does make sense, though perhaps not so strongly as the parent indicated. Young brains are more malleable - that’s pretty much a known thing - and learning at a young age sets in high knowledge and patterns of learning that follow us through adulthood.

If one learns a certain thing from a young age and it’s pretty much been driven in multiple ways - indoctrination whether intentional or otherwise - that’s a lot of stuff that’s been set pretty hard. Even it somebody is actively aware it’s bad it can be hard to adjust one’s inclination towards a certain way of thinking.

I’m not trying to make excuses for racism - because frankly a lot of those people don’t even try to adjust their thinking - but breaking free from one’s upbringing is not a small hurdle and I’d put it in similar terms to breaking a bad addiction.