system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What is different in the brain of a person having add or adhd?

In comparison to a average brain what is different in someone having a attention deficit disorder ?
I tried googling it but I couldn't find a real answer 
Also can someone please tell me what causes adhd ? Is it genetics ?
gpt
A 'normal' brain filters all the senses and focuses on what matters most. An ADHD brain rates more/most things as important and floods the brain with too much input. It's the difference between talking to a person and hearing what they say, and talking to a person and hearing traffic and static, seeing a blue poster, red pants, a stain on the carpet--is that a light?--smelling garlic, and somewhere, faintly under all that, hear their response.