If personal taste is something that emerges somewhat chaotically from personal experience and potentially genetics, then how can it belong to oneself and truly be personal? Surely, we don't like to think of our tastes as random; on the contrary, they define us. And yet if our tastes are something rational, then we might indeed be able to dispute them with some level of objectivity - some tastes would just be bad or good, and this could be proven.
Clearly this isn't the case - so it seems personal taste is neither a chaotic result of our interaction with our life experience, nor some sort of rational conclusion on the subjects of the taste. What, then, is personal taste?