Not sure I can agree about values remaining consistent. Values change, often, and sometimes even by the millions. I hate to use this as an example, but, Nazi Germany would certainly not have been possible if people's core values were static and unchanging.

Personally, my values have changed over time as well, as I've grown older, sharper, my lifestyle has changed, and so on. Granted, certain values have not, like I strive to be an honourable man, but then, those types of values are very vague and subjective. One man's definition of an honourable deed differs to another.

Again. I think the answer for this is too complex to chalk solely up to birthrite. We can, and do, regularly defy genetically programmed behaviours. So Ehh... Nehh...

Tl;Dr: insufficient information. More research required, but from what I have personally observed, I cautiously think it is a mix of genetic predisposition and intellectual, sentient choices.