Izuku was quirkless before, but then he got One For All. His mom saw him use his quirk in the Sports Festival, but she never asked him how he got his quirk. And Izuku told All Might that he hadn't told anyone about One For All, not even his mom. Yet, his mom never asked him about his quirk. Why didn't she say anything?
May be she thought he developed his quirk late in life?– PabloJun 10, 2020 at 12:49
@Pablo that is possible but she never asked about when he got his quirk and what his quirk was or anything else.– Sujal MotagiJun 10, 2020 at 14:11
@pablo - She is aware that he is quirkless. In the first episode (?) the doctor confirmed this with an X-ray.– user51291Jun 23, 2020 at 8:34
I can think of a few possible reasons why this would have happened.
Izuku's mother assumed that he developed his ability at some point, but chose not to use it often due to its side effects. In this case, she may not have mentioned it, realizing it may be a sensitive subject.
Izuku has a very close relationship with his mother, and people with these types of relationships can often tell a lot more about each other than most. His mother likely sense that, for whatever reason, he didn't want to talk about his quirk, and decided not to press the issue.
She asked Izuku offscreen, and he deflected her question somehow; which would end up resulting in the same effect as 1. or 2.
This is about Dekus mom knowing about the quirk I just watched season 3 episode "From Iida to Midoriya" and whilst on the train Deku has a flashback. Earlier at the hospital he was on the phone with his mom and she asked him do you have to go back to UA. We don't hear what he says until this flashback. He says mom All Might gave me everything, he trusted that I'd make the most of his quirk. This happens at just over 15 mins into the episode. I've watched this series many times and it's the first time I caught that confession. If you go back to the part where he's on the phone with his mom then fast forward to the confession he's still got the cellphone to his left ear and wearing the same clothes. The part that is confusing is a later episode when they talk to his mom , all might does say he's his chosen successor to be the next symbol of peace but she seems clueless to how he got his quirk. So I'm confused, The only other possibility is it's just his thoughts and it wasn't a real conversation, what do you think?
I don't remember Deku confessing but anyway it's in season 3. Deku got his quirk in season 1 so I was asking why his mom didn't ask about it back then. I got the answer though. She just thought he developed his quirk late. Feb 17, 2021 at 6:17
Sorry I didn't even realize this was just to answer a question, I was writing what I had just watched and was curious if others had seen that flashback and whether they thought Midoriya said it out loud to his mom or did he just think the statements we heard, whilest talking to his mom. I have no idea how to use forums properly this was only way I saw to talk about this general topic. Sorry I wasn't more clear when I posted.– Jenia63Mar 4, 2021 at 13:44
There are some scenes after the ending in season 2 episode 12 where izuku and his mom talk about him having a quirk.