The novel was either YA or teen, something I read in the 1980s. It was mass market at the time. It focused on a family, more specifically a teenage girl. One of the first scenes involved her riding on the subway with her older sister. The two see a group of young men attempting to rob an elderly woman. The older sister steps in and is eventually kicked in the stomach by one of the men. This incident reveals that the older sister is pregnant, something that causes some conflict for the family. It is around Christmas. The younger sister spends time with a teacher, in one scene driving around at night looking at the Christmas lights. She also spends a night with a girlfriend of hers, someone who is depicted as a free spirit. I seem to recall that the younger sister was torn by her feelings for her sister – resentment at the attention she was receiving, but also love.
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