Presumably, Lorraine's mother is a fairly attractive woman, or, at the very least, she was at one point. The narrator does not give readers a lengthy physical description of Mrs. Jensen, but we are told that she has long, beautiful brown hair. Lorraine also tells readers that her mom is a very pretty woman "when she smiles." Unfortunately, Mrs. Jensen hardly ever smiles, so her beauty hardly ever shows. This parallels her thoughts about men. At one point, Mrs. Lorraine was married and in love, but like her beauty, her faith in men and her love toward the opposite sex has faded and become hard.
Mrs. Jensen caught her husband cheating on her, and she divorced him. Soon after the divorce, he was killed. These two tragic events in such close proximity to each other profoundly affected Mrs. Jensen. Her faith in men and her outlook on life were both completely crushed. She now believes that men only have one thing on their mind, and she repeatedly warns Lorraine about this. She even goes so far as to threaten Lorraine about the consequences of being in a car with a boy.
She's always warning me about getting into cars and things like that. When she goes to work on a night shift, she constantly reminds me to lock the doors and windows, and sometimes she calls on the phone if she gets a chance and tells me again. Beware of men is what she's really saying. They have dirty minds, and they're only after one thing. Rapists are roaming the earth.