Why does the brain only blockout certain bad memories?

Question

In my past Ive had many bad memories, but some that my parents told me of I had forgotten, but they werent the worst ones.

Answer 1

Maybe your brains couldn't be bothered to keep all the memories on the foreground because you already had so many really really bad memories to cope with. I do think however that all your memories are there, somewhere in your brain and that it's maybe important to explore what's there. Sometimes memories, although ,seemingly, forgotten can influence you in your present life.

Answer 2

It is a defense mechanism. It also may be that you were too young to remember. Also, think of it this way: your brain stores so much memory-at the same time you forget certain things. I wouldn't worry too much about it.

Answer 3

Some of them didnt touch you when you were younger and so your brain kind of "stored" them in the back
either something was so traumatic that your brain tried --once again-- to "store" it in its back.Actually it's your brain's try to erase it.But its not actually erased,it's just stored in the back of your mind,waiting to be recalled either by a story told by someone that was present in the event,either by hypnosos or such things.