Two of the reasons that luke gives for another child being in the sports family house

Luke has had to deal with increasing restrictions on his freedom: first, he cannot go outside; next, he cannot go downstairs; then he cannot eat dinner with the family at the table or even spend time with his mother. These restrictions come at a time when his brothers are growing up and he is realizing that he will never be able to make friends or form a family like they have. He thinks another child in the house would be good.