What are the financial obligations of the parents of a high-needs child after that child reaches adulthood?

Parents have a moral obligation to raise their children until they can leave the nest, which may be after age 18 and may be never. Children who, for a legitimate reason, aren’t capable of self-support can continue to receive child support from both parents even after they otherwise wouldn’t. A judge will almost never order an arrangement that is as generous as what you could negotiate and agree to on your own.