In my opinion, I think it really depends on what events took place in the past life. Due to our free will, we may avoid or enter traumatic experiences that might shape our future personality. A person who was mentally scared by bullying in a past life may be a naturally shy and insecure person in this life. I do think little things that don't matter too much tend to stay with us. Studies by Dr. Ian Stevenson show that people may carry a taste for certain foods over to another life. For example, a person whos past life was in Japan may really enjoy raw fish, as was the case of an American child who remembered a Japanese life, and could also speak Japanese by around the age of three. Career choices may also be carried over. I don't just mean that, for example, if someone was a fisherman in a PL, they'll be a fisherman in this life. I mean that we could make a career out of something personal from a PL. If someone a soul loved, or indeed themselves, died if a fire, for example, they may choose to be a firefighter in this life.