Dill’s broken family is significant in To Kill a Mockingbird because his lack of a father contrasts sharply with Scout and Jem’s experiences with their father Atticus.
The Finch children are highly interested in Dill, but they do not probe the whoppers he tells. They realize that he makes up stories because he is saddened that his father has abandoned him and his mother seems disinterested. There are few times when the children actually push him about his father.
I asked Dill where his father was: "You ain't said anything about him."
"I haven't got one."
"Is he dead?"
"Then if he's not dead you've got one, haven't you?" (ch 1)
Scout is confused, but Jem tells her to change the subject. Dill’s fantastic stories about his father being an important man, like a train engineer, come out repeatedly, but the children usually don’t challenge them.
The Finch family is not an intact family either. The children’s mother is dead. Yet their father raises them with a curious combination of detachment and affection. When Dill’s father never materializes, the children realize that he is a little lost. They accept him into their family.
One of the key themes in the story is accepting people for who they are. Dill has not yet come to terms with his lack of a father, but the Finch children support him and do not make an issue of it.