I think we're a combination of nature and nurture and each person has a different "percentage" of each for each trait they're born with, just like for different colored eyes, etc. But, unlike eye or hair color, personality traits don't necessarily automatically get expressed, can be affected by the person's environment/nurturing. But shy people often have shy parents, for example, so it would be unusual for the person to become more outgoing unless they had a grandparent or someone else who took care of them more often than the parent did who was outgoing. But there's loads of traits we don't know much about or think of; sense of direction (do you get lost easily, probably one of your parents does too) and little stuff that can influence other stuff depending on how things are combined. That's what makes us very unique just like we may look like a parent or grandparent or other relative but we're not at all exactly like them or our siblings. That relates to the "soft" traits too, not just the obvious physical ones. If one's father is good at math and good at music but outgoing and you are good at math and good at music and shy you may end up an actuarial instead of an orchestra conductor. So, I think we all get born with our various physical and all other traits but what happens with the non-physical ones depends on environment and nurturing and how they're combined with all the other traits we have.