Theodore Roosevelt was born on October 27, 1858, in New York to Martha Bulloch Roosevelt and Theodore Roosevelt Sr., he was their second child and first son. He was named after his father, Theodore Sr., and was sometimes called "Thee" or "Teddy" as a nickname. He was a seventh generation Roosevelt. As a child and throughout his lifetime, Theodore suffered from severe asthma, becoming so bad that it would nearly suffocate him at times. His father, who refused to have a sickly child, would constantly carry him around, hoping that Theodore's lungs would become stronger. Because of this, Theodore always admired his father that would protect him. He would follow the strenuous exercise regiments that his father set on him to become stronger. He would do weightlifting, gymnastics, and any other activity that would give him endurance. Slowly, his asthma decreased to lesser degrees. .
Theodore hardly ever went to school because of his sickly nature, so he was instructed by his Aunt Annie, that lived with the family. He spent much time reading, and this is where he became obsessed with natural history, a passion that stayed with him throughout his lifetime. He would even kill animals and stuff them himself when he was a teenager. Theodore wanted to attend Harvard in the fall of 1876, but did not have all the preparation necessary. Nevertheless, he completed three years of college preparation in less than two years. He also passed all of his preliminary exams. He entered Harvard in late September 1876. .
During the summer of 1877 Theodore published his first work entitled The Summer Bird of the Adirondacks in Franklin County, NY. While he was away at college, his father died at the young age of 46 from stomach cancer. Theodore made it home only hours after his father had died. The loss of his father would have a profound effect on Theodore as seen later in his life. Yet, he returned to Harvard the following year, and was during this time that he met Alice Lee.