It's important to remember that responsible researchers on behavior genetics (such as the researchers that I am about to quote here, from a review article) point out that just because an individual difference is "inborn" (heritable) does NOT mean that it cannot change under environmental influence. "Moreover, even highly heritable traits can be strongly manipulated by the environment, so heritability has little if anything to do with controllability. For example, height is on the order of 90% heritable, yet North and South Koreans, who come from the same genetic background, presently differ in average height by a full 6 inches (Pak, 2004; Schwekendiek, 2008)."

Johnson, Wendy; Turkheimer, Eric; Gottesman, Irving I.; Bouchard Jr., Thomas (2009). Beyond Heritability: Twin Studies in Behavioral Research. Current Directions in Psychological Science, 18, 4, 217-220

http://people.virginia.edu/~ent3c/papers2/Articles%20for%20O...

Indeed, there are psychologists who are fully aware of the research base on heritability of the "Big 5" personality dimensions you mention who nonetheless research interventions to change people's personality along one or more of those dimensions. It is already well known to personality researchers that personality changes over the course of life (from early childhood to old age) much more than most people think it does.

> just because an individual difference is "inborn" (heritable) does NOT mean that it cannot change under environmental influence

On the flip side, just because a feature isn't heritable, doesn't mean it can be changed through an environmental intervention. Many people assume that what isn't strictly genetic, must me malleable but there may be more than a fair bit of just randomness there or hard to alter circumstances (pre-natal environment, remnants of infections).

Good point. It probably is.