Lets start at the very beginning for both captains, and for purposes of discussion, we are going to discount the 2009 reboot of Star Trek and its sequel, and rely exclusively on established canon as Abrams films occur in another time continuum which significantly changes Kirks childhood and Picard hasnt even been born yet. Comparing both captains childhoods, we see some differences. Kirk was born in Iowa and the son of a Star Fleet officer George Kirk. The novel, Final Frontier, written by Vonda McIntyre, apocryphally situates George as the commander of the as-yet unnamed experimental starship (which we later discover to be a Constitution-class starship. Kirks mother, Winona, was pregnant on board the USS Kelvin while her husband served as its first officer, meaning that Kirk began life in embryo on board a starship. Though born in Iowa, Kirks fathers career took his family all around the galaxy, living on different colonies and planets like Tarsus IV. James Kirk credits his father as his inspiration to serve in Star Fleet. In contrast, Jean-Luc Picard was born in rural France. He was the son of a vineyard-owner who consistently looked for greater challenges than farm-life could offer. Picard was never satisfied with the limits of rural living and fled to Star Fleet Academy. Along the way he achieved substantial recognition in athletic and academic areas, even considering becoming an archeologist at one point. If there was a ceiling to break, Picard broke it. However, Kirks life is markedly different because all he knew growing up was Star Fleet. Kirk was destined to become a Star Fleet captain because of his lifestyle in space and his fathers influence. Despite Picards erudite upbringing, the edge has to go to Kirk because of pre-eminent position Star Fleet held in his life while growing up. Plain and simple, his lifestyle prepared him to think like a Star Fleet captain before he even put on a Star Fleet uniform. He was born to be a captain.