Tattoo disagreement

So for my 18th birthday present my sister and I are getting matching tattoos and I want this sunflower on my forearm. My mom said I can’t get it on my forearm and if I do I’m getting kicked out. She thinks people look trashy with arm tattoos. My sister has a tattoo on the back of her shoulder and my mom still can’t stand to look at it and it’s been 3 years.