# murderer's thumb

**URL:** <https://boards.straightdope.com/t/murderers-thumb/95182>\
**Category:** Factual Questions\
**Created:** [November 25, 2001, 9:08pm UTC](https://boards.straightdope.com/t/murderers-thumb/95182 "2001-11-25T21:08:40Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![momkultra](https://avatars.discourse-cdn.com/v4/letter/m/f14d63/32.png) [@momkultra](https://boards.straightdope.com/u/momkultra)\
**Post date:** [November 25, 2001, 9:08pm UTC](https://boards.straightdope.com/t/murderers-thumb/95182/1 "2001-11-25T21:08:40Z")

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I’ve heard of this several times, but need more information on it. I believe it relates to an extra wide thumbnail in males, extra height, and a tendency to aggressive behavior. I think it is a genetic problem. Does anyone have any better info???

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**Author:** ![Qadgop\_the\_Mercotan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/qadgop_the_mercotan/32/83_2.png) [@Qadgop\_the\_Mercotan](https://boards.straightdope.com/u/Qadgop_the_Mercotan)\
**Post date:** [November 25, 2001, 9:13pm UTC](https://boards.straightdope.com/t/murderers-thumb/95182/2 "2001-11-25T21:13:37Z")

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are you talking about XYY syndrome? I’ve never heard of the thumb thing, though. Here’s a brief link on the syndrome:

[XYY syndrome](http://www.aaa.dk/turner/ENGELSK/Xyyen.htm)

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**Author:** ![Qadgop\_the\_Mercotan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/qadgop_the_mercotan/32/83_2.png) [@Qadgop\_the\_Mercotan](https://boards.straightdope.com/u/Qadgop_the_Mercotan)\
**Post date:** [November 25, 2001, 9:22pm UTC](https://boards.straightdope.com/t/murderers-thumb/95182/3 "2001-11-25T21:22:31Z")

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BTW, the link between XYY syndrome and excessive aggression is quite tenuous, and dismissed out of hand by many authorities. They are taller than XY males, though.

Try this link for even more info:  
[http://www.aaa.dk/turner/ENGELSK/xyy.htm#contents](http://www.aaa.dk/turner/ENGELSK/xyy.htm#contents)

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**Author:** ![bibliophage](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bibliophage/32/7615_2.png) [@bibliophage](https://boards.straightdope.com/u/bibliophage)\
**Post date:** [November 26, 2001, 2:32am UTC](https://boards.straightdope.com/t/murderers-thumb/95182/4 "2001-11-26T02:32:18Z")

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My favorite pathology site has a page about [XYY](http://www.google.com/search?q=cache:oJOgM55X6X0:www.pathguy.com/xyy.htm)

> [@](#):
>
> The famous Nielsen letter in Lancet Sept 7, 1968 claiming that the prevalence of XYY men in prison was “25-60 times as high as the prevalence in the general population” remains a shocking example of how to mislead the public using small-sample statistics – there were only two XYY’s identified in the study.  
> . . .  
> When you control for the high testosterone levels, the most recent published study (from 1984) showed there is no over-representation of XYY men in prison.

I’m not sure that XYY what you’re thinking of. I can’t find any indication of anything unusual about the thumbnails of XYYs. They may have a greater liklihood than normal of having seizure disorders, of having bad acne, and of having abnormalities of the urogenital system or the teeth.