There is no "true self" but most people still claim there is

 I've said that both directly and indirectly more than once on this site. So has philosopher friend Massimo Pigliucci in various ways.

Now Vice has an in-depth look at this illusion.

Several good takeaways.

First is that people believe their ethics and morals are at the core of a true self.

Second, riffing on behavioral psychology, when people are asked to think about potential changes to their moral selves, when they make good changes, they say it's getting more in touch with that true self. When they imagine making negative changes, it's a "dark side" or something that is not part of their true self. Shades of loss aversion or similar! And, it's not just WEIRD; Hindus and Buddhists from India and Tibet have the same stance.

Third, under blood is thicker than water, if we have wingnut relatives acting like wingnuts, many of us say that's "not their true selves." (I don't have a problem saying it is.)

Fourth, outside people we know, this flips, especially in America, with a punitive criminal justice system.

The story goes on to talk about things like psychological essentialism and moral certification. Give it a read.