A study released a little over a week ago,

问题：

A study released a little over a week ago, which found that eldest children end up, on average, with slightly higher IQ’s than younger siblings, was a reminder that the fight for serlfdefinition starts much earlier than freshman year. Families, whatever the relative intelligence of their members, often treat the firstborn as if he or she were the most academic, and the younger siblings fill in other niches: the wild one, the flirt.
These imposed caricatures, in combination with the other labels that accumulate from the sandbox through adolescence, can seem over time like a miserable cat. entourage of identities that can be silenced only with hours of therapy. But there’s another way to see these alternate identities: as challenges that can sharpen psychological skills. In a country where reinvention is considered a birthright, many people seem to treat old identities the way Houdini treated padlocked boxes: something to wriggle free from, before being dragged down. And psychological research suggests that this ability can be a sign of mental resilience, of taking control of your own story rather than being trapped by it.
The late-night bull sessions in college or at backyard barbecues are at some level like out-of-body experiences, allowing a re-coloring of past experience to connect with new acquaintances. A more obvious outlet to expand identity--and one that’s available to those who have not or cannot escape the family and community where they’re known and labeled —is the Internet. Admittedly, a lot of the role-playing on the Internet can have a deviant quality. But researchers have found that many people who play life-simulation games, for example, set up the kind of families they would like to have had, even script alternate versions of their own role in the family or in a peer group.
Decades ago the psychologist Erik Erickson conceived of middle age as a stage of life defined by a tension between stagnation and generativity-a healthy sense of guiding and nourishing the next generation, of helping the community. Ina series of studies, the Northwestern psychologist Dan P. McAdams has found that adults in their 40s and 50s whose lives show this generous quality - who often volunteer, who have a sense of accomplishment - tell very similar stories about how they came to be who they are. Whether they grew up in rural poverty or with views of Central Park, they told their life stories as series of redemptive lessons. When they failed a grade, they found a wonderful tutor, and later made the honor roll; when fired from a good job, they were forced to start their own business.
This similarity in narrative constructions most likely reflects some agency, a willful reshaping and re-imagining of the past that informs the present. These are people who, whether pegged as nerds or rebels or plodders, have taken control of the stories that form their identities.
In conversation, people are often willing to hand out thumbnail descriptions of themselves: "I’m kind of a hermit." Or a talker, a practical joker, a striver, a snob, a morning person. But they are more likely to wince when someone else describes them so authoritatively.
Maybe that’s because they have come too far, shaken off enough old labels already. Like escape artists with a lifetime’s experience slipping through chains, they don’t want or need any additional work. Because while most people can leave their family niches, schoolyard nicknames and high school reputations behind, they don’t ever entirely forget them.

A recent study shows that

A．the firstborns and younger siblings are often treated differently.

B．higher IQ holders in a family are always the eldest.

C．the firstborns in a family often become more academic

D．the younger siblings are more likely to be ill-treated.