[12] Nevertheless, he was energetic and mischievously inquisitive.[13] His lifelong interest in zoology began at age seven when he saw a dead seal at a local market; after obtaining the seal's head, Roosevelt and two cousins formed what they called the "Roosevelt Museum of Natural History". Having learned the rudiments of taxidermy, he filled his makeshift museum with animals that he killed or caught; he then studied the animals and prepared them for exhibition. At age nine, he recorded his observation of insects in a paper entitled "The Natural History of Insects".[14]
Roosevelt's father significantly influenced him. His father was a prominent leader in New York's cultural affairs; he helped to found the Metropolitan Museum of Art, and had been especially active in mobilizing support for the Union during the American Civil War, even though his in-laws included Confederate leaders. Roosevelt said, "My father, Theodore Roosevelt, was the best man I ever knew. He combined strength and courage with gentleness, tenderness, and great unselfishness. He would not tolerate in us children selfishness or cruelty, idleness, cowardice, or untruthfulness."