Why would anyone want to have kids?

Because from infancy they've been bombarded with this "be fruitful & multiply" B.S.   

I need someone to light my cigarettes and pour my vodka when the arthritis associated with old age catches up to me.

They love kids and want to procreate.

Because they love kids.

It’s mandatory for our species to survive. Why people want kids is because it’s part of our DNA to want kids 

From what I've heard / understand..?

- Maternal / paternal instincts, that are hard to explain and rationalize. 

- This sense of wanting to "leave something behind".

- Loving kids, and wanting a life that revolves around raising them, having experiences with them, etc.

- Feeling like one is a family.

- Feeling like having kids gives one's life an increased sense of meaning and purpose.

..Speaking as a childfree by choice woman, who's NEVER wanted them, I find it pretty dang hard to relate to. But hey… This is me trying to (badly) play devil's advocate. I suppose. ;)

Because if you raise them right, they bring you joy.