How is it that siblings (兄弟姐妹) can turn out so differently? One answer is that in fact each sibling grows up in a different family. The firstborn is, for a while, an only child, and therefore has a completely different experience of the parents than those born later. The next child is, for a while, the youngest, until the situation is changed by a new arrival. The mother and father themselves are changing and growing up too. One sibling might live in a stable and close family in the first few years；another might be raised in a family crisis, with a disappointed mother or an angry father.
    Sibling competition was identified as an important shaping force as early as in 1918. But more recently, researchers have found many ways in which brothers and sisters are a lasting force in each others' lives. Dr. Annette Henderson says firstborn children pick up vocabulary more quickly than their siblings. The reason for this might be that the later children aren't getting the same one-on-one time with parents. But that doesn't mean that the younger children have problems with language development. Later-borns don't enjoy that much talking time with parents, but instead they harvest lessons from bigger brothers and sisters, learning entire phrases and getting an understanding of social concepts such as the difference between 'I' and 'me'.
    A Cambridge University study of 140 children found that siblings created a rich world of play that helped them grow socially. Love-hate relationships were common among the children. Even those siblings who fought the most had just as much positive communication as the other sibling pairs.
    One way children seek more attention from parents is by making themselves different from their siblings, particularly if they are close in age. Researchers have found that the first two children in a family are typically more different from each other than the second and third. Girls with brothers show their differences to a maximum degree by being more feminine than girls with sisters. A 2003 research paper studied adolescents from 185 families over two years, finding that those who changed to make themselves different from their siblings were successful in increasing the amount of warmth they gained from their parents.

单选题     The underlined part 'in a different family' (in Para. 1) means ' ______ '.

单选题     In terms of language development, later-borns ______.

单选题     What was found about fights among siblings? ______

单选题     The word 'feminine' (in Para. 4) means ' ______ '.