There are few people who can embarrass you more than your own family.
That's because they know all of your deepest, darkest secrets. They watched you grow up and all the weird phases you went through, both physical and social. All the strange TV obsessions, your love of a specific anime character that was borderline creepy, some terrible band you fangirled over and now wouldn't want to be caught dead listening to - they know it all.
But sometimes families can embarrass you because, well, they're just embarrassing people themselves.