This question originally appeared on Quora:
Answer by Jay Wacker, my daughter's father since 2013
The moment for me occurred when my daughter was about 2 weeks old and I had that first "oh shit" moment where I developed a terrifying pit in my stomach over my daughter that you think you've done something irreparably bad.
I'd fallen asleep on the couch. After waking in my sleep-deprived state, I didn't remember for a moment that I had a daughter. All of a sudden, I remembered why I was so tired and then I couldn't remember where I put my daughter before I had passed out. I developed a terrible pang of guilt for forgetting that I had a daughter and a growing sense of panic because I'd lost my daughter. And then I found her (in the bassinet sleeping 2 feet away) and I felt irrationally wonderful, not silly in the least. I made sure she okay, waking her up in the process and loving the sound of her cries. I looked at the clock and I'd been asleep for less than 5 minutes from the last time I'd looked at the clock.
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Answer by Marco North, Creative Dir. • Bittersweet Group / Publisher • Bittersweet Editions
Apart from the obvious sentimental connections, I would offer this. There are plenty of milestones that signify you are a new parent - the kick of the child inside, the buying of cribs and changing tables ... the first birthday, etc.
The true realization is when you start to make sacrifices. You sell the motorcycle. You stay in, instead of going out drinking. You run home from work. You stay up late, worrying about things like immunizations and if your child's new friend has betrayed them. You move to another country if they are kidnapped there.
It is when you change your own life that the realization is complete.
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Answer by Sanjay Sabnani, Asian Dad
I realize that the most expected answer is to refer to that often photographed moment when your baby grasps your big finger for the first time, but in my case it simply wasn't true. I felt emotional at the birth of all three of my daughters, but I did not feel like a dad. I could see in my wife's entire being that she felt something bigger and more powerful than I did- something biological, but what I felt was a mixture of relief and pride.
Fatherhood crept upon me gently without much warning like mild joint pain in the morning. It happened when my eldest child was 10 and the others were 8 and 5 respectively. I cannot pinpoint the date or event that triggered my realization, but I know it happened because the consequence of that realization still terrifies me to this day.
I realized for the first time that it was OK if I didn't do everything I wanted to do in life, or achieve everything I had set out to achieve because now I had children who could do and achieve things for me. This is a surreal feeling because prior to that moment, I had been very selfish in how I thought of this world and what its relationship was to me. Knowing that my life would now be about helping my children achieve bigger and better things was stunning to me. For some reason my logical and excessively rational mind felt a biological satisfaction in having been a partial genetic contributor to offspring that would in turn (hopefully) carry this genetic legacy onto the next generation and so on.
I realized I was a dad when I realized that I cared more about the success of my children than of myself, and that I knew somehow that there is part of me contained within each one of them.