I was pretty against having kids until age 26 or so, and by the time I was 29 I’d fully changed my mind. Here are the reasons.
1 - sociobiology
Unwillingness to forego one of the most intense and unique animal relationships possible:
The key to the sociobiology of mammals is milk. Because young animals depend on their mothers during a substantial part of their early development, the mother-offspring group is the universal nuclear unit of mammalian societies.
2 - failing
When I was younger, my major objection to having kids was that it would interfere with my career. I cared a lot about my career and looked forward to transitioning from a student who worked really hard and excelled in classes to a professional who worked really hard and excelled in the workplace and also earned a boatload of money. (I also knew I wasn’t the kind of person who could juggle both a career and a family.) But then it turned out that I wasn’t a hard worker, I just loved studying and taking exams. I don’t have a career or the relationship to a career I envisioned, so the desirability delta went down.
3 - friedman
Seven years ago, I went to a meetup hosted by an economist who liked historical reenactments. His three adult children were in SCA garb, served the guests food from a medieval Persian cookbook, and sat around arguing with him (and the rest of us) about economics. It was my first encounter with a family where the children shared interests with their parents and talked like peers. It fundamentally changed my mind on what families could look like.
4 - payment
Similar story: I visited my friend’s family two years ago, and stayed in his teen daughter’s room because there had been an in-house auction to determine whose room would go to the guest. She won and was monetarily compensated for it.
In addition to acquiring another example of a Relatable Family Where The Members Actually Like Each Other, I found my friend and his spouse’s financial philosophy appealing and became be compensated for pregnancy and childcare by my spouse. 20% of my objection to having kids was objection to the financial arrangements of traditional marriage (which in my view screwed over both of my parents when their relationship broke down). The exact arrangement we’ll come to is still up in the air – and it may be that we can’t improve much on the traditional approach – but I feel better having the option to negotiate for a financial arrangement that to me feels more autonomy-preserving, egalitarian, and respectful of my labor and opportunity costs.
5 - sustain
I knew I didn’t want to be pregnant, didn’t particularly like infants, didn’t want to interact with toddlers for more than an hour (I like them but get fatigued and have to go lie face down to recharge), which seemed like a good argument to not have kids. But I also simulated being 60 and childless and it felt distinctly bad. In particular when I asked myself the question of whether my current projects, hobbies, and relationships were enough to sustain me for the rest of my life, the answer was, surprisingly, no.
6 - connection to future
Another surprise when I asked myself questions about the childless-at-60 timeline was that I noticed for the first time that I want a connection to the coming generations. Weird. Where did that come from? Pretty sure it wasn’t in my psyche 5 years ago. But when I glanced through the right area of my values.txt file, I saw it was there.
7 - spouse
It was hard not to notice that my spouse would make an excellent dad (more so than I would make a good mom, frankly), and also that we have complementary skill sets and preferences qua parents.
8 - be lazy
I read “Selfish Reasons to Have More Kids” after I’d already decided to have kids, but when I was discussing the decision with friends, multiple of them brought the book up. Its basic argument is that we (I suppose I mean Americans and East Asians here) invest in our children well past the point where it matters, which increases the quality of life difference between parents and non-parents, which sucks because lots of people would enjoy raising kids if the unnecessary expectations were dropped.
Once I actually read the book, I found it suspect – I stopped reading when Caplan described a study and then drew an inference that didn’t logically follow – but the conclusion seems true based on observation and common sense. My own parents and I had a lot of conflict over piano lessons because proficiency in an instrument was expected in their milieu. My mom regularly fought me to make me eat breakfast (to this day I don’t eat in the morning, my body just isn’t made for that) even though it would have been fine to send me off to school with a banana to tide me over until lunch. People trade away health and career points to breastfeed even though the evidence is shaky that it matters. My sister is pursuing a zero screen policy with her child and said this choice significantly increases work and emotional toll.
Once I noticed I was the type to be an overworked neurotic parent and that I’d built in my own terrible personality as an assumption when simulating how hard childrearing would be, I also noticed I could (with effort) not be that person and have an easier time. So my expectations of parenting changed.