As a parent of a 2yo myself I think it's a bit of both. I definitely changed a lot, am more focused on being a parent and also feel lees existential and depressed because I have a new and almost full time project which is raising my daughter to the best of my ability. But I also noticed some changes that I can describe as growth. I no longer have trouble getting up early, and I go to bed early as well if I need to do so the next day. This is basic responsibility that I didn't have before. I also help more around the house and take time to fix things that I would've just left and procrastinated on for months before (changing a bulb, improving my office, etc). I've got a promotion as well and am doing better at my job, even though I have less time overall. I think this is because I'm more focused than before, which is unexpected since I work from home. I have also become more motivated to work on personal projects. I've started homebrewing since my daughter was in the womb, got back into chess and even did some gardening. So a lot of positive change in my life. I cannot say if this would have happened regardless of my daughter but I am definitely in a much better place than I was before

I agree with the other two responses.

Dealing with your own kids you start to understand humanity better. You understand your parents more, one of the funny things that happens, is you catch yourself responding to things the same way your parents did. Sometimes that's good, other times that's bad. This leads to self-evaluation. You have to ask how did I feel when my parents did this? What did I hate about my parents parenting style, what did I like?

If you don't have children, it's purely a theoretical question, the stakes are null. With your own children the stakes are the emotional, physical and intellectual health of your kids, it has to be taken seriously.

On the flip side you realize that we are all just kids in adult bodies. I see my children do things and I see parallels in my own behavior, or in the behavior of others. So not only do you understand your parents better, you understand yourself and humanity better.

Aside from getting a better understanding of human nature, you also have to start making decisions about your own needs vs the needs of others, in this case your children, and your co-parent. If your kid is throwing up at 2am, guess what, you can't just deal with it tomorrow. You start checking the weather to see does my kid need a coat, a rain coat, a t-shirt? As a side effect you start paying more attention externally. Questions like "how is my kid feeling right now?", or "why did they just do that?". Which means your empathy increases, and your emotional intelligence.

All of this presumes the ability to self-reflect. Which is something a large number of people lack, including parents. Basically if you ever see bad parents you will notice the common thread is lack of self-reflection and awareness. It's holding on to your past self which ultimately hurts your children, and your personal growth.

I lived for a while single and without kids. When I finally got married and became a father my feeling was that it was like I had been playing a video game and stayed far too long in the first level. It's fun there, and easy, but there's a whole lot more out there. It can be harder, scary, relentlessly demanding - but also deeply fulfilling and wonderful. (I'd write more but there's a crying baby I've got to go help)

Weird, I felt the reverse. Staying the straight course married with kids is the first level where it's easy and many others are running the same program, and CPS or divorce loom if you actually seriously alter the routine or take serious dangerous risks. Society pretty much approves of the 'family' path. Being single was like hard mode where you could basically make your life as dangerous or as interesting as you like, and you didn't have to worry about risking the life of your wife or child. When I was a homeless single male, I could have been run over by a car in the street and no one would have given two shits, other than maybe to pickpocket my corpse.

You could argue you are better because you know more.

I'm still a software engineer and into fitness. After having kids I also had some experience with parenting.

By observing kids development you can also understand and experience how people grow into the adults you see everyday and I definitely think I understand psychology more.

Being a parent is also a great journey of self discovery. You'll learn how you react to stress, you'll realise things about your own childhood, you may uncover a series of problems you may have.

As much as I loved to think of myself as someone thinking older than my age, I was definitely less mature before having kids.