family history with breast cancer

young0and0worried

hi i no i just posted but i read my post again and i sounded a bit selfish. Not only am i worried about my future but my mothers and older sister.  My mom is 40 this august and keeps putting off the mammagram she has had ones a few years ago but nothing since everytime i bring the subject up it results in a fight i have tried everything from guilt trip to crying to yelling everything. Her mother died frim this i dont want mine.  And my sister shes 20 young but our history not so good.  Is she likely to get it to.  They wont talk to me about it. I need advice please