All characters in Lost that have flashbacks in time have some type of conflict with their parent/s.
For example, Jack's dad is an alchoholic who interferes with Jack's work and pressures him too much to the point he hears him in an intercom that has been dead for years, due to dehydration, and hears Christian (Jack's Dad) saying "let it go, Jack".
Another example, Hugo's dad left him when he was only a young boy, and once Hugo won the lottery, his father came back, for the money!
Continuing, Kate's a fugative, which naturally would cause conflict with parents, which in this case, she kills a man abusive to her mother, which she later found out, was her father. Also, her mother, Diane, disowns Kate.
John Locke's dad is conman, and treated him like a son when Locke finally finds him. Then he cons him for his kidney and later throws Locke out of a window from an eight story building because Locke found out he was about to scam another woman and her family.
There are many more characters with issues with their parent/s.