Oh no my mother found p**n on her computer i need help and advice!?

Question

ok well my mom found a p**n site on her computer she called me to her computer and had the site highlighted and said what is this? and i was like idk and she was like did you go here and i was like no and she said only one other person has been on this computer and it was my cousin and she thinks it was her so she is probably gonna confront her and then they gonna find out it was me

but it is NORMAL for guys my age to look at p**n, she should be more worried if i didn't

how do i tell her its normal and i shouldnt get punished for it?????