I just want to know the right thing to say to my brother because he keeps wanting to be the exception and barely even trying and gets mad at me when he realizes he said the wrong name

i have recently come out as non binary to my family and they are really accepting but my twin brother keeps calling me my deadname and using she/her pronouns my mom says that while it can be annoying with my brother not trying she says that i shouldn't be suprised if one day my whole family is using...