Lois is the loving wife of Peter.  She is the only person in the family who actually knows what the reasonable thing to do.  She loves Peter even with all his crude antics.

Lois teaches piano lessons out of their living room.  The rest of her free time is wasted doing housework and looking after Stewie.

Lois comes from a wealthy family.  She met her husband, Peter, when she and her wealthy aunt were staying at a hotel resort.  She feel in love with Peter because he was so different for all the rich snobs who were trying to court her.