This is a big part, and all cows have a huge ego. Many have used the phrase "carry on my legacy" or something along those lines.
I happen to enjoy the incel/loveshy cows for some reason and a running trait they see kids as living proof, you've had sex. Now you or I can brag we've banged 45908608596 girls and these people are so angry and hateful even if you had sex tapes of each and every sexual encounter of your life, they would cry and scream photo shop. Having a kid and DNA test (yes some weirdos have said they would get it just to prove they had sex) is undeniable someone bumped uglies with you.
Sadly, I can name a few cows that
@Strong Tranni Role Model was not joking about.
Most cows lack long term thinking, and don't see what a serious ordeal a kid is. They don't have the common sense or planning skills to own a pet (or do it safely/well) so to them a kid is just a check book off the to do list of life.
Needless to say those who do manage to reproduce are awful parents and doom their own children to be the next gen of lolcows or worse, I'm looking at you Cecily.
Depressing most of all, some cows we know only because they already have kids and are woefully neglectful or abusive.