How can someone just genuinely not care about their child?

There are so many parents, both moms & dads, that just up and leave their children.. Or lose custody and don’t fight to get it back. My mother lost custody of me when I was 8 & my sisters were 1, and 4. She never attempted to get us back. She when on to develop a more extreme addiction to crystal meth, and never looked back.

My sons father never even attempted to get to know him. He left when I was 4 months pregnant. I don’t understand how someone could just flat out not care, not have guilt, and not want to have their children.

How could somebody do this? How can someone just NOT care? Call me crazy, but I freak out leaving my son overnight, more less just giving up on him & not caring.