For example, the changes can be other molecules aside from DNA. Like something that attaches to DNA and prevents a gene from being expressed. What makes such a

For example, the changes can be other molecules aside from DNA. Like something that attaches to DNA and prevents a gene from being expressed. What makes such a thing interesting is if it persists through cell divisions, and especially interesting if it is passed down to the next generation. And it turns out that, surprisingly, such things exist.