My family seemed pretty perfect until my folks got divorced when I was thirteen. They both assured me that it wasn't anyone's fault. As it turns out, while I wasn't the reason, I was the catalyst.
My Dad started to notice that, as I aged, I shared no physical features with him. He confronted my Mom about it and she revealed the truth; I was the product of a drunken one night stand. My Mom and Dad had dated briefly and then broke up. Shortly after the break-up, Mom went to a party and hooked up with some guy. When she discovered that she was pregnant, she contacted my Dad and told him that I was his son. They got married shortly after I was born.
Dad agreed that no one else needed to be told, but the fact that the whole marriage had been built on a lie brought a lot of bad shit to the surface and they decided to call it quits.
My perfect family was shattered, but what's worse a lot of terrible things have come to the surface in the years since that have poisoned all but a few of my memories of growing up.