14 year old and 28 year old

My step dad has a better relationship with a 14 year old than my mom or me last night we were in the pool and he (accidentally) hit her but and she laughed and when I accidentally hit her butt she hits me and yells at me And she will be twerking on him in the pool and she is on him like they sit right beside each other in the pool and she touches him alot every time she comes over (everyday) she ask where he is She even said she rather a 28 year old touch her than me I asked why she got mad when I accidentally touched her but she did't when my dad touched her

Unless I misunderstood, it sounds like she understood what your father did was an accident and what you did was intentional. Getting hit and yelled at are typical consequences for putting your hands on other people's bodies in places they don't belong.