History Main / XYY

An extra Y chromosome. A common enough genetic disorder (1 out of 1,000 biologically male humans) that, at its worst, has only two symptoms: above-average height and an increased susceptibility to learning disorders.

In fiction, however, being XYY makes you a criminal! It's simple logic:
* A Y chromosome makes you male.
* Therefore, an extra Y chromosome makes you ''more'' male.
* Men are more aggressive and violent.
* [[InsaneTrollLogic Therefore, an extra Y chromosome makes you even]] ''[[InsaneTrollLogic more]]'' [[InsaneTrollLogic aggressive and violent.]]

This trope is likely to show up in crime dramas and other works that involve both bad guys and genetics researchers or genetic typing. It's usually either the reason the bad guy is bad or an aggravating factor in his badness.
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!!Examples

[[AC:{{Film}}]]
* Used in ''{{Alien}}''. All the XYY males are automatically put on a penal colony.
* Referenced in ''ScaryMovie 3''.
* The biology research institute in ''TheCatONineTails'' is researching it while the murders happen around it.

[[AC:{{Literature}}]]
* ''[[http://en.wikipedia.org/wiki/The_XYY_Man The XYY Man]]'' began life as a series of novels by Kenneth Royce, featuring the character of William (or Willie) 'Spider' Scott, a one-time cat-burglar who leaves prison aiming to go straight but finds his talents still to be very much in demand by both the criminal underworld and the British secret service. Scott has an extra "y" chromosome that supposedly gives him a criminal predisposition - although he tries to go straight, he is genetically incapable of doing so.

[[AC:LiveActionTV]]
* The Season 5 finale episode "Born to Kill" of ''CSIMiami'' referenced this trope. A couple knew that their son had this condition and constantly treated him with suspicion because of it. [[spoiler:When their daughter accidentally kills their other daughter by pushing her down the stairs, she claimed ''he'' did it on purpose; this is what actually turned him violent.]]
* Played with in ''CriminalMinds'', where a killer claims that he's XYY, and that's why he kills. However, Rossi replies that the study linking that condition to criminal behaviour was debunked years ago.
* An episode of ''ForeverKnight'' centers on a legend that a (female) vampire who mated with an XYY male "higher than high, under the light of the full moon" would become human. The XYY human did have extra violent tendencies.
* ''[[http://www.imdb.com/title/tt0075601/ The XYY Man]]'', the first of Kenneth Royce's novels, was transferred to British television by Granada TV, in a three-part adaptation with Stephen Yardley playing Scott. The adventures of Scott caught the public imagination and ten more episodes followed in 1977.

[[AC:RealLife]]
* Richard Speck falsely claimed that he was XYY and that it was why he killed all those women.
* The source of this idea was some medical studies from the 1960s, which claimed that the XYY genotype actually could cause a propensity for violent behaviour. This came from a study that revealed a slightly higher incidence of XYY among jailed convicts than among the general population. Which was either a coincidence, or a [[ArtisticLicenseStatistics false correlation]], that didn't account for how XYY men (like people with other chromosomal abnormalities) have an increased risk of learning disabilities that might hinder their ability to ''get away'' with a crime. Though this idea has been discredited, it still pops up now and then.
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An extra Y chromosome. A common enough genetic disorder (1 out of 1,000 biologically male humans). At its worst, its only symptoms are above-average height and an increased susceptibility to learning disorders.

* [[InsaneTrollLogic Therefore, an extra Y chromosome makes you even ''more'' aggressive and violent.]]

In fiction, however, XYY makes you a criminal! It's simple logic:

UnfortunateImplications abound.

An extra Y chromosome. A common enough genetic disorder (1 out of 1,000 biologically male humans). You might not even know you have it, since the body will only take instructions off one. At its worst, its only symptoms are above-average height and an increased susceptibility to learning disorders.

In fiction, however, XYY makes you a known criminal! It's simple logic:

* Men are more agressive and violent.
* [[InsaneTrollLogic Therefore]], an extra Y chromosome makes you even ''more'' agressive and violent.

An extra Y chromosome. A common enough genetic disorder (1 out of 1,000 biologically male humans). You might not even know you have it, since the body will only take instructions off one.

* As stated above, ''[[http://en.wikipedia.org/wiki/The_XYY_Man The XYY Man]]'' began life as a series of novels by Kenneth Royce, featuring the character of William (or Willie) 'Spider' Scott, a one-time cat-burglar who leaves prison aiming to go straight but finds his talents still to be very much in demand by both the criminal underworld and the British secret service. Scott has an extra "y" chromosome that supposedly gives him a criminal predisposition - although he tries to go straight, he is genetically incapable of doing so.

* [[InsaneTrollLogic Therefore,]] an extra Y chromosome makes you even ''more'' agressive and violent.

* An episode of ''CSIMiami'' referenced this trope: a couple knew that one of their sons had this condition and constantly treated him with suspicion because of it. [[spoiler:When their daughter accidentally killed their other son by pushing him down the stairs, she claimed ''he'' did it on purpose; this is what actually turned him violent.]]

An extra Y chromosome. A common enough genetic disorder (1 out of 1,000 biologically male humans). You might not even know you have it, since the body will only take instructions off one.

* Men are more violent.
* [[InsaneTrollLogic Therefore,]] an extra Y chromosome makes you even ''more'' violent.

!!Examples:

* An episode of ''CSIMiami'' referenced this trope: a couple knew that one of their sons had this condition and constantly treated him with suspicion because of it. [[spoiler:When their daughter accidentally killed their other son by pushing him down the stairs, she claimed ''he'' did it on purpose; this is what actually turned him violent]].

* An episode of ''{{Forever Knight}}'' centers on a legend that a (female) vampire who mated with an XYY male "higher than high, under the light of the full moon" would become human. The XYY human did have extra violent tendencies.

[[AC: TV shows]]

* ''[[http://www.imdb.com/title/tt0075601/ The XYY Man]]'', the first of Kenneth Royce's novels, was transferred to British television by Granada TV, in a three-part adaptation with Stephen Yardley playing Scott. The adventures of Scott caught the public imagination and ten more episodes followed in 1977.

[[AC: Literature]]

* As stated above, ''[[http://en.wikipedia.org/wiki/The_XYY_Man The XYY Man]]'' began life as a series of novels by Kenneth Royce, featuring the character of William (or Willie) 'Spider' Scott, a one-time cat-burglar who leaves prison aiming to go straight but finds his talents still to be very much in demand by both the criminal underworld and the British secret service. Scott has an extra "y" chromosome that supposedly gives him a criminal predisposition - although he tries to go straight, he is genetically incapable of doing so.

* The source of this idea was some medical studies from the 1960s, which claimed that the XYY genotype actually could cause a propensity for violent behaviour. This came from a study that revealed a slightly higher incidence of XYY among jailed convicts than among the general population. Which was either a coincidence, or a [[ArtisticLicenseStatistics false correlation]], that didn't account for how [=XYY=] men (like people with other chromosomal abnormalities) have an increased risk of learning disabilities that might hinder their ability to ''get away'' with a crime. Though this idea has been discredited, it still pops up now and then.

* The biology research institute in ''TheCatONineTails'' is researching it wgile the murders happen around it.

* An episode of ''{{Forever Knight}}'' centered on a legend that a (female)vampire who who mated with an XYY male "higher than high, under the light of the full moon" would become human. The XYY human did have extra violent tendencies.

* [[InsaneTrollLogic Therefore, an extra Y chromosome makes you even]] ''[[InsaneTrollLogic more]]'' [[InsaneTrollLogic violent.]]

* The Huron Indians once boasted that they were "men and double men, with two penises" instead of men and women, and would [[RapeIsFunnyWhenItIsMaleOnMale "make women of your men"]], so this is OlderThanTheyThink.

* An episode of {{Forever Knight}} centered on a legend that a (female)vampire who who mated with an XYY male "higher than high, under the light of the full moon" would become human. The XYY human did have extra violent tendencies.

http://en.wikipedia.org/wiki/The_XYY_Man : The XYY Man began life as a series of novels by Kenneth Royce, featuring the character of William (or Willie) 'Spider' Scott, a one-time cat-burglar who leaves prison aiming to go straight but finds his talents still to be very much in demand by both the criminal underworld and the British secret service. Scott has an extra "y" chromosome that supposedly gives him a criminal predisposition - although he tries to go straight, he is genetically incapable of doing so.

http://www.imdb.com/title/tt0075601/ : In 1976 the first of Royce's novels was transferred to British television by Granada TV, in a three-part adaptation with Stephen Yardley playing Scott. The adventures of Scott caught the public imagination and ten more episodes followed in 1977.