Genetics, along with hormones and upbringing, may play a part in sexuality, according to a study。

　　Researchers claim it is known that there are well-established traits which differ between girls and boys, with, for example, boys more likely to engage in 'rough and tumble' play。

　　Children who later become gay or lesbian are more likely to differ from these expected traits, or gender conformity, said a team from Queen Mary University in London。

　　Between 50 to 80 percent of gender non-conforming boys become gay, and around a third of non-conforming girls become lesbian。

　　Now, doctors Andrea Burri and Qazi Rahman believe that in girls, genes may be partially responsible for gender non-conformity and, by association, sexual orientation。

　　They followed a group of 4000 female twins, asking them about their sexual attractions and gender non-conformity。

　　They discovered genetic influences on sexual orientation (25 percent) and childhood gender nonconformity (31 percent)， reports journal PLoS One。

　　Dr Rahman said: ‘We found that there is a connection between these mental traits and how sexual orientation develops。

　　‘One idea is that there is an association between these psychological traits and sexual orientation because they all develop under common biological drivers; like the development of brain regions under the influence of genes and sex hormones。

　　‘We think environmental factors and genetics drive other mechanisms, like exposure to sex hormones in the womb, to shape differences in gender nonconformity and sexuality simultaneously.’

　　Dr Rahman said the results showed non-conforming behaviour came 'from within', and proved that mental health issues such as depression which have been associated with such behaviour was due to negative reactions from others。

　　一项研究显示，除了荷尔蒙和教育方式外，基因也会对性取向产生影响。

　　研究人员称，众所周知女孩和男孩的特质之间存在着根深蒂固的区别，比如男孩更喜欢打闹。

　　伦敦玛丽皇后大学的研究团队称，后天变成同性恋的孩子往往不具备与自身性别一致的个性和特质。

　　那些表现和自身性别不符的男孩有50%到80%后来成了同性恋，而那些“假小子”女孩则有约三分之一变成了同性恋。

　　现在，安德烈•布里博士和卡齐•拉曼博士认为，女孩表现出异性特质以及性取向出现问题，有一部分可能是由基因造成的。

　　他们跟踪调查了4000名双胞胎女性，询问她们的“性趣点”以及她们的行为和自身性别是否相符。

　　他们发现，基因对于性取向的影响占了25%，童年时期行为和性别的偏差占了31%。这些发现发表在期刊《公共科学图书馆•综合》上。

　　拉曼博士说：“我们发现，在这些心理特征和性取向的发展之间存在着某种联系。”

　　“一种想法是，这些心理特征和性取向是相互关联的，因为它们都是在同一个生物机体驱动下发展的，就像大脑区域的发育同时受到基因和性激素的影响。

　　“我们认为环境和遗传因素驱动着其他机制的发展，例如受到子宫内性激素的刺激会形成不同的性取向，以及造成行为和自身性别相符或偏差。”

　　拉曼博士说，研究结果显示，和性别不符的行为源自“体内”，并证实与这种行为相关联的抑郁等心理健康问题是由来自他人的负面反应造成的。