Who here supposes anyone is a tabula rasa? Who here supposes anyone emerges in this life fully formed and actualized? This is a spurious dichotomy that is erected time to time based on cultural norms and stipulations - much of it propagandising to suit others desires and ends.
How are those beliefs working out for you?
The same goes with IQ. I don't think any average person could ever train their intelligence to be, say, John von Neumann. Thus it is not _completely_ mutable. He was a genetically superior specimen by every account and evidenced such from a very young age. But a good 15-20 point boost, especially if we did not train ourselves to our fullest before? Maybe. I used to process more slowly, now I process faster, because I pushed to think quicker. Thus it is not completely _fixed_, either. Definitely we can eradicate racial IQ gaps, I believe (average Black-White IQ gap in the US is 15 points favoring Whites, by the way.), Rushton et. al. be damned. If I remember right, in some places it was actually done, thus proving its possibility. (Interesting tidbit the racists seem not to address: Bhutan's and China's people are both “Mongoloid Asian" race by racist theory – but Bhutan has IQ 85, China at 105, at least using racists' own data sets. I wonder also what the IQ for rural China vs. urban wealthy China looks like. I suspect the 105 number comes from having a large proportion of the latter in the sample.)
The personality is a constellation of aspects that we all show to varying degrees, many of which are in fact out of our control, but some of which nevertheless are capable of being adjusted in accordance with various forms of conditioning. It is in that constellation that we find what the personality is. Emphasizing minute aspects and exaggerating them doesn't constitute the whole personality. This is remarkably uninformative as an article.
The supposition that the personality is completely fixed or completely mutable is simply false. There are fundamental constraints to how the personality can be manifested. Histrionic personalities are perhaps those most inclined to believe that their personality is truly self-determined, but they'd also be mistaken.