Check out this doc I watched last night, it's on the BBC Iplayer so I dont know if it will work outside the UK but anyways...
http://www.bbc.co.uk/iplayer/episode/b0 ... rsonality/
Basically it examines the growing scientific evidence that while certain personality traits such as anxiety or nervousness are activated by certain genes, and thus the brain works in specific ways because of this. However, there is a growing body of evidence that certain genes can change based on behaviour, and thus the tendancy towards these negative emotional responses diminishes over time. From a PUA persepective, this is evidence that the positive thinking and confidence techniques etc that a lot of PUA theories talk about can have a real positive, potentially permanent effect. Its all very interesting I assure you, well worth a watch.