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Twins, and the reasons behind why some peoplehave them and others don't, has fascinated scientistsfor centuries.

雙胞胎本身，以及為什么有的人能生出雙胞胎有的人卻不能，幾個世紀(jì)以來一直是科學(xué)家感興趣的問題。

They are relatively common - occurring once in 100pregnancies - and while the cause of non-identicaltwins has been linked to genetics, the genesinvolved had not been identified until now.

雙胞胎近年來相對來說更加普遍了，每100個產(chǎn)婦中就會有1位懷有雙胞胎。雖然已經(jīng)有證據(jù)證明異卵雙生與遺傳因素有關(guān)，但至今還沒有人成功鑒別出自發(fā)性異卵雙生的基因。

Researchers have pinpointed two gene varians related to twinning, and one can play a majorrole in the age of a girl's first period, age at menopause and infertility.

研究人員已經(jīng)發(fā)現(xiàn)了兩種與雙胞胎有關(guān)的基因變異，其中一種對女孩的月經(jīng)初潮年齡、更年期年齡與生育能力起著非常重要的作用。

The breakthrough was made by Dr Hamdi Mbarek and Professor Dorret Boomsma from theVrije Universiteit in Amsterdam.

這項(xiàng)重大突破是由阿姆斯特丹大學(xué)的哈姆迪·穆巴拉克博士和多雷特·博穆薩教授發(fā)現(xiàn)的。

The first gene variant is close to the gene coding for the secretion of follicle stimulatinghormone, called the FSHB gene. This hormone is released by the pituitary, the small brainregion that governs almost all major hormonal events in the body.

第一個基因的突變與分泌卵巢激素的被稱為FSHB的基因密碼相近。該激素是由負(fù)責(zé)著幾乎人體所有主激素分泌的腦垂體分泌的。

The second variant relates to the so-called SMAD3 gene and is likely to be involved in the waythe ovaries respond to follicle stimulating hormone.

第二個突變與所謂的SMAD3基因相關(guān)，可能與卵巢對卵泡刺激素的反應(yīng)方式有關(guān)。

Both variants result in the multiple follicle growth needed for the development of non-identical twins.

這兩個突變都會導(dǎo)致多重卵泡的生長，這是異卵雙胞胎的基礎(chǔ)條件。

Non-identical twins, medically known as dizygotic, develop from two separate eggs fromseparate follicles fertilised by separate sperm cells. Whereas identical twins develop from oneembryo that splits in half, dizygotic twinning thus starts with a multiple ovulation.

醫(yī)學(xué)上定義的異卵雙胞胎，是指兩個不同卵泡中單獨(dú)的兩個卵子，和兩顆精子結(jié)合發(fā)育而成。與之相反，同卵雙胞胎是由一個卵細(xì)胞一分為二發(fā)育而來的，因此異卵雙胞胎的起因是超數(shù)排卵。

Discovery of the main genes behind the mystery of spontaneous dizygotic twinning was longawaited, and is of great scientific interest and clinical importance,' said Professor Boomsma.

博穆薩教授表示：“人類早就希望能解開自發(fā)性異卵雙胞胎的秘密，這一直是科學(xué)界和臨床研究中重要的課題。”

However, there are still more genes to be found that influence spontaneous dizygotictwinning.

不過，目前還有很多與自發(fā)性異卵雙胞胎有關(guān)的基因有待發(fā)現(xiàn)。