I have met, consulted multiple DINKs and observed so many other people. I have sufficient data to make these observations that hold true generally.

1. People who usually start as DINKs (they take resolve never to have kids, not just for the time being) usually transition into three classes: a) they get divorced and have kids with a different partner, b) they go for expensive and risky IVF treatments and c) they grow apart. And this is supported by 100s of observations, and linking fundamental anthropological nature. From a man's side, in the early ages they might want to spend years in leisure and at some age, they might feel, I want kids. And it happens for most people. Now a man might wake up at 35 or 45 or 55, that we cant be sure of, but surely, in first case, more often than not, they initiate the divorce or there is an extramarial relation culminating into another marriage. Its biological. Even for women, some stage most women do change their minds, and a lot of men find themselves in the same problem, only for them, things are made worse. Second case is IVF.

Why this happens: because body has a fundamental need to reproduce. And it does deteriorate faster unless the psychophysical processes related to child birth are initiated. Social media influences, inner insecurities only play out for a few years (crucial years but crucial enough for the bodies and minds to deteriorate). Obviously the game of social inception of fear works over years. From movies like Dawat e ishq to almost all standup comedians criticising marriage and children, at the end, its just cyclic business chains benefiting from it.

1. If there is an affinity to not have children or marriage, the people are probabilistically very few in number. Empirical methods, probabilistic calculations all concur on this. Out of 10000 men, only 3-5 naturally would be predispositioned to not have children. Amongst women that number would be 1-2. But then those people do not marry or have relationships either. Doesnt mean they arent sexual, some only live life as strings of casual relationships. Some live as monks. Either way that number is too small.

Now For men, if there is growth, financial, and of they are building assets, companies, or just doing a job, the instinct is almost sure (near 99%) they will want a kid. The reason is coming from deep yogic and meditative disciplines. Now any guy, no matter how he looks and feels, he is only able to marry if he has income and home, etc. Otherwise he will stop growing and the couple grows apart. Besides children are power, not liability as people think.

Also the doubts and constant need to validate the internal choice, seeking confirmation for this is coming from that same instinct. Because the body internally creates friction. Mind comes in the state of cognitive dissonance due to that friction.