Family can be both a destructive and creative force in this novel, but no matter what, it's really important to gods, demi-gods, and mortals alike. The Greek gods are all related to each other, and they sure do have their share of family issues – there is so much tension between them that one wonders how they have survived for so long without ripping each other to shreds. Well, that's exactly the situation we find when we begin reading The Lightning Thief: the brothers Zeus, Poseidon, and Hades don't trust one another. This lack of trust nearly leads to World War III.
Similarly, we see how destructive family can be when campers like Luke feel unloved and unclaimed by their mortal parents. Even the demi-gods and gods want to feel like they are part of a family – it's not just a mortal thing. At the same time, we watch as Percy matures and grows wiser as he learns more about his father and as he realizes that his father is truly proud of him. Though his home life in Queens, NY is troubled thanks to Smelly Gabe, Percy's relationship with his mom is what makes everything OK. Their little family is what Percy lives for.