Travis Hirschi's theory concerning delinquent behavior stems, primarily, from his belief that delinquency rose (and continues to rise) as a direct result of a breakdown in the family unit. His theory was proposed in the late 60s, a time in America when rock and roll, drugs, and rebellion against "the man" were becoming more popular than many social institutions such as organized religion, educational institutions, government, and the family.
When he speaks of the first of four variables, attachment, Hirschi suggests that delinquent behavior is less likely in humans who have attachments to others. He is not merely saying humans must have such attachments, but that those attachments must be meaningful. Therefore, his list logically begins with the family and moves outward. Delinquent behavior is least likely to come from individuals who are meaningfully attached to their parents first, then peers (or siblings), teachers, religious leaders, and finally other members of a community and authority figures.