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"Gay Liberation"，installed in Christopher Park, is a life-size bronze sculpture by George Segal that depicts two same-sex couples, female and male. A man's sexual orientation appears to be determined in the womb, a new study suggests.  Past research by Dr. Anthony F. Bogaert of Brock University in Ontario and colleagues has shown that the more older brothers a man has, the more likely he is to be gay. But it has not been clear if this is a prenatal effect or a psychosocial effect, related to growing up with older male siblings. To investigate, Bogaert studied 944 gay and straight men, including several who were raised with adopted, half- or step-siblings or were themselves adopted. He reasoned that if the relationship between having older male siblings and homosexuality was due to family environment, it would be seen whether or not a man's older brothers were biological or adopted. Bogaert found that the link between having older brothers and homosexuality was present only if the siblings were biologically related -- this relationship was seen between biological brothers who were not raised together. The amount of time that a man was reared with older brothers had no association with sexual orientation. "These results support a prenatal origin to sexual orientation development in men and indicate that the fraternal birth-order effect is probably the result of a maternal 'memory' for male gestations or births," Bogaert writes in his report in PNAS. A woman's body may see a male fetus as "foreign," Bogaert explains, and her immune response to subsequent male fetuses may grow progressively stronger. "If this immune theory were correct, then the link between the mother's immune reaction and the child's future sexual orientation would probably be some effect of maternal anti-male antibodies on the sexual differentiation of the brain," he suggests. (Agencies)

一項最新研究認為，男性的性取向可能在娘胎里就已經(jīng)決定了。 加拿大安大略省布魯克大學的安東尼·F·博格特博士和他的同事過去對男性性取向問題進行過研究。研究結(jié)果顯示：男孩子的哥哥越多，他成為同性戀者的幾率就越大。但有一點不能確定，“與哥哥一起長大影響男性性取向”是先天因素還是受后天心理影響？ 為了研究這一問題，博格特對944名男性同性戀和異性戀者進行了調(diào)查，這其中包括幾名自己或者兄弟是被領養(yǎng)的、與兄弟有一半或無血緣關系的男性。博格特認為，如果哥哥影響弟弟的性取向是受家庭環(huán)境影響，這就要看哥哥是親生的還是領養(yǎng)的。 博格特發(fā)現(xiàn)，只有弟弟和哥哥之間有血緣關系時，弟弟才會受影響成為同性戀，即使是他們不一起長大，這種影響也存在。而且，與哥哥一起長大的時間長短與性取向沒有什么聯(lián)系。 美國國家科學院院刊刊登了博格特這一調(diào)查報告，報告中寫道，“這些研究結(jié)果證明了男性的性取向由先天因素決定，同時暗示，哥哥影響未出生弟弟的性取向，可能源于懷孕媽媽對男嬰的生理記憶。” 博格特解釋說，也許母體將男性胎兒視為“異物”，因此懷孕媽媽的免疫體系對后來的男性胎兒反應越來越強。 博格特提出：“如果這個免疫理論正確，那么媽媽的免疫反應影響孩子將來的性取向可能是因為媽媽分泌的反男性抗體影響了胎兒大腦中決定性取向的機制。” (英語點津陳蓓編輯)