Neuroscience makes it clear now that our brains have unlimited learning potential. When it doesn't seem that way, about ourselves or others, it's because we can have stories that we don't. We tell ourselves and each other stories that we have limits.
Growth capacity becomes more clear to the extent we work on learning new things that matter to us. We don't know what we can do until we give time to learning and practicing. This is true for us and others. What we have done so far is not a reliable assessment of what's possible.