I have a bro who is 1 year old and his teeth are crooked, could it be because he uses a pacifier?

I doubt it. The average 1 yr old has about 8 teeth and enjoys a pacifier for its self directed soothing. At that age crooked teeth most often represent a natural crooked eruption rather than a distortion caused by sucking. A dental exam could tell for sure, but crooked baby teeth are common &don't necessarily mean adult teeth will be. Even crooked teeth should be kept healthy to preserve space for adult teeth.
Probably not. Has to do with intensity and duration. Finger or thumb much more damaging than pacifier. Teeth probably genetically crooked. Have your child seen by a qualified pediatric dental specialist. Don't wait until 2 or 3, please go now.
Possibly yes. At age one if there is crooked teeth then it is the pacifier. Does he have an open space between upper and lower teeth when he bites down? When he stops eating pacifier very quickly teeth go back to be normal again. My daughter is 3 still taking pacifier!
Crooked teeth. Maybe, but a lot of teeth come in crooked and then straighten out on their own. At such a young age i wouldn't worry too much about it. Also if they baby teeth are crooked, this is not an indication that the adult teeth will come in crooked. At 1 years of age, it would be good to try and cut back on the pacifier. As they get older it's even harder to stop. Good luck.
Maybe . At this age it doesn't indicate anything nor does it matter. Let your bro enjoy his 1 year age...