I think @BackforGood is right. I grew up in a family like that. I thought there were late people and early people and it was down to what kind of person you were. Not something you could choose or change for yourself. I always stayed silent when "early people" talked about how rude and arrogant it was and how late people thought they were better than everyone else. It wasn't true for me, i always felt bad, but I just didn't know how not to be late.
It wasn't that I could make stuff that was important to me either. I missed the start of movies. I used to aim to be an hour early for important things like interviews so I could get there on time. I got a warning for constantly being late to work.
I think it was starting driving that changed me. And probably the invention of google maps around the same time. All of a sudden I didn't guess how long it would take me. The sat nav told me exactly.
Everyone says "I can't believe it's not obvious that you should look at the clock, work out how long it will take you and leave on time!" But when you grow up in a family where no one even starts looking for their keys until five minutes before they have to be there, because it's "only five minutes' drive" (when actually the drive takes 8 minutes and parking another 3), you don't learn how to do this. When your family never ever build in contingency time, or value showing up early, and when you spent your childhood sitting strapped in the car while they dashed back inside the house to do one last thing, or take out the bins or lock the windows or grab a jacket they can't immediately locate. You just think this is how it works for everybody and some people are lucky that all the tasks line up to allow them to leave on time.
I had to train myself as an adult, 5 years out from living with my family. I know it sounds stupid but 20 years of conditioning really will brainwash you into thinking punctuality is fate, not a choice. But it's a choice I make (mostly successfully) now. Still get a bit over-optimistic about that one last thing sometimes though.
Learning the exact journey times I'll need, always having my keys/jacket/bag in the same place, and allowing extra time are the things that help me.