Arguably, the sole purpose of life is to procreate. You can live a purely unfulfilled life and die the most miserable wretch possible, but if your children have

Arguably, the sole purpose of life is to procreate. You can live a purely unfulfilled life and die the most miserable wretch possible, but if your children have children, and their children do as well, and so on, it doesn't matter - genetics doesn't care (barring some kind of recessive hereditary illness responsible for this original misery). And perhaps this is why so many people get divorced, and even why there are so many bastard children and deadbeat fathers/parents: in some inherent way, such people have already fulfilled some unnamed biological goal and have no real incentive to pursue it further. Because a family, being a committed parent, is a societal abstraction that many need not bother with. Certainly you can see this in other animal species.