Is it normal that my memory doesn't start until age 13?

Repressed memories are repressed for a reason. If your mother can't talk about it then it will be difficult to find the key to your mystery. And I'm sorry to say it is likely traumatic. You could try hypnotherapy but be prepared for some bad memories to surface. I hope for your sake, that this isn't true. Ask yourself what you will gain from this knowledge. But understand it is maternal instinct to protect their children. It may be very difficult for her to talk about.

I'd say....sure as hell something happened, but ask yourself if you really want to know? There might be a good reason your brain is preventing you from remembering. On the other hand it must be really frustrating.
Do you have anybody else to ask? Father, grandparents, family friends,...?

I don't think it's normal. You and your sister's memory randomly start at the same time? You're mom sounds suspicious about it too. You should have her tell the truth.

I talked to my mother about my child hood and realized there were somethings i didn't remember at all, some unhappy memories. You might have a lot of repressed memories

If she doesn't wana tell u. And look u into the eye. Ofc sumthn is up ...

Often when a very traumatic event(s) like abuse, molestation, or sexual abuse occurred, a person's subconscious will block them out from memory as a coping mechanism. I've read about this many times before, and the fact that you and your sister both have this implies some kind of familial trauma. These memories, if this is indeed the case, may be brought back to consciousness by therapy.

I remember very well being 3-13 years old. I'm 25 and I don't want speak with some people because they made fun of me when I was 6-7.

You and your sister are obviously clones of your parents real children, who must have died in an accident or something when they were 10 and 13. There's probably a whole farm of you out there somewhere in case you die as well

for me its like before 5

You found area 51 and CIA erased your memmory

Your mother is hiding smth from you

Actually whats really weird is that you can remember what age your memory started :)

If she won't answer your questions then obviously something must jaw happened...

You could use this as a script for a horror film. Make lots of money lol

Maybe you and your sister got brainwashed

I think it's normal I don't remember nothing from before I was 8

I don't think anything's up.
Before two years ago I had the crappiest memory, I don't remember anything before 10y old. It happens. Move on.
I think we can all safely assume you has 13 birthdays, what more do you need to know?

You're probably just thinking too hard into things.