BBC News｜出生顺序如何影响你的健康？

How birth order could affect your health

Host: Birth order has fascinated scientists for decades, with questions over whether it affects traits like intellect and personality. But new research suggests it could actually impact your health.

A study involving more than 10 million Americans found associations with everything from anxiety to autism. One of the authors is Ben Kramer from the University of Chicago. He spoke to Shaun Ley.

Ben: Siblings act as a natural experiment because they share genetic data, but we know they have different environments. However, when we compare siblings to one another within family, we can control for anything that they share by virtue of being in the same family, like household socioeconomic status, shared parental genetics, and parenting style.

Shaun: Around 400 or so medical conditions which you looked at, I think 150 showed an association with birth order. Can you explain that?

Ben: We can't claim causality. We can only claim that there is an association between a lot of diseases and birth order. These are population-level associations, not individual predictions, but it helps us see different patterns in large data sets.

The allergy results are a strong example of the biological validity of the data set, and that later-born children have lower odds of allergic rhinitis, food allergy, and asthma, which typically fits the idea that early microbial exposure from older siblings may shape immune development.

Another striking finding is that substance abuse had significant excess in the second born child. So there may be some sort of first born influence on the second born child in terms of using and abusing substances.

Shaun: One of the examples that you quote in this research is that older children or the oldest child in a family might be statistically more likely to suffer from diseases like psychiatric illnesses, for example. Is there any explanation of why that might be or any factors you can rule out?

Ben: A plausible biological explanation is that first pregnancies may physiologically be different from later ones. The maternal immune system and placenta are adapting to pregnancy for the first time and later pregnancies may benefit from biological memory which could modestly affect early brain development.

Shaun: Do you think this kind of research could eventually provide something really quite helpful for parents when they're bringing up families of multiple children?

Ben: These large data sets are really good for looking at patterns and from those patterns we can kind of do deeper dives into even different variables relating to the siblings, like how age gap might affect disease.

And once confirmed, they can lead to real-world intervention, talking about how certain behavioral aspects of raising a child might lessen the burden of certain incidents for disease.

词汇表
autism [ˈɔːtɪzəm] n. 自闭症，孤独症
sibling [ˈsɪblɪŋ] n. 兄弟姐妹
genetic data [dʒəˈnetɪk] 基因数据，遗传数据
by virtue of [ˈvɜːtʃuː] 由于，凭借，因为
household socioeconomic status [ˈhaʊshəʊld ˌsəʊsɪəʊˌiːkəˈnɒmɪk ˈsteɪtəs] 家庭社会经济地位
parenting style [ˈpeərəntɪŋ] 养育方式，育儿风格
causality [kɔːˈzæləti] n. 因果关系，因果性
population-level adj. 群体层面的，人口层面的
validity [vəˈlɪdəti] n. 有效性，正确性
odds [ɒdz] n. 可能性，几率
allergic rhinitis [əˈlɜːdʒɪk raɪˈnaɪtɪs] 过敏性鼻炎
food allergy [ˈælədʒi] 食物过敏
asthma [ˈæsmə] n. 哮喘，气喘
microbial exposure [maɪˈkrəʊbiəl ɪkˈspəʊʒə(r)] 微生物暴露
striking [ˈstraɪkɪŋ] adj. 显著的，引人注目的
substance abuse [ˈsʌbstəns əˈbjuːs] 物质滥用，药物滥用
psychiatric [ˌsaɪkiˈætrɪk] adj. 精神病的，精神病学的
rule out 排除，消除
plausible [ˈplɔːzəbl] adj. 貌似合理的，可信的
pregnancy [ˈpreɡnənsi] n. 怀孕，妊娠
physiologically [ˌfɪziəˈlɒdʒɪkli] adv. 生理上，生理学方面
maternal [məˈtɜːnl] adj. 母体的，母亲的，母性的
placenta [pləˈsentə] n. 胎盘
modestly [ˈmɒdɪstli] adv. 适度地，轻微地
bring up 养育，抚养
dive [daɪv] n. 深入探究，投入，钻研
variable [ˈveəriəbl] n. 变量，可变因素
age gap [ɡæp] 年龄差距
confirm [kənˈfɜːm] vt. 证实，确认
intervention [ˌɪntəˈvenʃn] n. 干预，介入
lessen [ˈlesn] vt. 减轻，减少

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