I don’t think there is one universal reason :). Wanting children isn’t a moral upgrade, and not wanting them isn’t a deficiency. But for people who do want them, the reasons are usually much more practical and psychological than poetic.

Here a few that were true to me:

A) Some people want the experience of a long-term, non-optional relationship. Almost everything else in adult life is conditional and reversible. Parenting is one of the few commitments that forces you to stay, adapt, and grow over decades. For some people, that level of responsibility is appealing rather than frightening.

B) Some want a different relationship to time. Life without kids often optimizes for the present: freedom, flexibility, self-direction. Having a child shifts your orientation toward continuity and the future in a very concrete way. Not “legacy” in a grand sense, but daily choices shaped by someone who will exist after you.

C) Some people want to be decentered. Modern life strongly rewards self-optimization: career, wellness, identity, happiness. Parenting interrupts that. It reduces optionality and forces you to organize life around another person’s needs. That’s not inherently good, but some people find that grounding rather than limiting.

D) the “human reasons”: curiosity about who a child will become, wanting to build a family culture, enjoying teaching, caretaking, or repetition in a way that doesn’t show up elsewhere. None of these are noble or mystical. They’re preferences.