Why does Bilbo feel an inner struggle between the two sides of his ancestry, the Bagginses and the Tooks?

Family lineage is another important factor that shapes identity in The Hobbit. Throughout Middle-Earth, one’s prospects, character, and social position are linked closely to family heritage. Bilbo’s conflicting feelings of fear and courage, for instance, are portrayed as a struggle between his Baggins side and his Took side, referring respectively to his father’s and his mother’s families. Thorin is prompted to seek the treasure under the mountain because it is his birthright, passed down from his grandfather, Thror. Bard’s heroism is in part attributed to his having descended from the lords of Dale. Whereas race is primarily a determinant of one’s moral standing, family has more to do with one’s specific personality: Bilbo is good because he is a hobbit, but he is adventurous because he is a Took.