you inherited their genes, and maybe they fucked up something during pregnancy that made you ugly, but its definitely not your fault,
my parents smoked around me as i was a child and i developed asthma as a consequence, we are products of our environment
there are almost no people whitout traumatic experiences, and these traumatic experiences can be severe, so as to for example cant understand the emotional state of the child, or even resent the child for crying and throwing a tantrum or doing something stupid, some parents just cant handle it and are overwhelmed by the problems with their kids.
and because they are in a bad emotinal state from this and underlying psychological past traumas, the treat the child whiout compassion, whitout feeling for how the child feels, with no connection to the emotional world of the child.
for example, there are hundreds of reasons why the time with your parents traumatized you and made living difficult,
another reason could be narcissist parents that are more concerned about how the crying child makes THEM feel rather then how the child feels and what you can do to connect and maybe eliviate the pain.
but idk your exact situation you need to do research into psychology and traumas if youre really interested.
but a good sign is if you visit your parents do you feel bad afterwards or during? almost all the time?
if thats the case its most likely unhealed trauma that gets retriggered everytime you visit them (thats why i stopped seing them)
dont feel pressured to visit them and be nice to your parents just because society has the bullshit rules to honour your parents, for what? for fucking each other?
edit: the explanation is not very good, i was mostly talking about my own situation,
but my point is, if you feel like shit alot its probably your parents fault