Why do some young mothers trick a guy into believing that they're pregnant and it's their child when years later they find out that it's not even theirs should he still pay child support or not?

It is easy for a new mom to convince herself that her baby has features that look like the man she thinks fathered her child. And unless the race is distinctive, the supposed father won't be able to refute the claim without DNA or a confession from the mother that cannot be refuted by DNA. Many times, when the true father is identified by DNA, the mom is just as shocked as the supposed father. Don't make the mistake of assuming every woman who finds out at a later time, the father of her child, was trying to fool the man. There is a better than 50% chance she was fooled herself.

It might not be a trick. When a woman is having sex with more than one man during her fertile period, she might not know who the father actually is. Depending on the woman, she might choose the man she hopes the father will turn out to be because she thinks he will stay around and help her raise the child.

When there is doubt DNA does not lie.

Why do trans people get so deeply offended when a stranger misgenders them, especially when it's a first encounter? I've been socially transitioned for 4 years and it just feels like a waste of energy to be so hurt by it.

If there is one than one man she is intimate with, that woman has zero chance of knowing which one fathered the child. A woman cannot know the exact instant when she became pregnant. Conception just doesn't work that way. There is no changes at all in her body that she can recognize as pregnancy until the 2nd month. I didn't know I was pregnant with my first child until I was already 3 full months pregnant. I wasn't stupid or uninformed, just didn't have any of the usual symptoms. Never had one moment of morning sickness, none of the cravings others talked about, didn't experience unusual tiredness.