Think of it like this: There are two newborn babies. One baby is very calm and easygoing, but the other baby is very demanding and vocal. The babies have just been born, but they both seem to already personalities. This proves that our personality has a genetic component, but this does not mean that we are just born with our personality. To prove this, researchers have found that a large number of twins have similar personalities. These findings suggest the heritability of some personality traits, implying that some aspects of our personalities are largely controlled by genetics (“Genetics, the Brain, and Personality”). Heritability is what researchers call the degree to which behavioral variations within a population can be accounted for by genes. Heritability is what is found to make up a lot of one's personality. One of the very first cases documented that linked genetics and personality was in 1858 with a man named Phineas Gage. He worked as a blasting foreman for a railroad company, and due to a faulty blast, a railroad spike was blown through his head. Somehow, Phineas Gage survived this atrocious accident. The railroad spike went through his frontal lobe in his brain, and he started to experience many changes in his personality that scientists now know are associated with this area of the brain. The changes in Gage's personality after his brain injury spurred interest in the biological factors involved in personality and implicated the frontal lobe as an important area associated with higher-order personality functions (“Phineas Gage