Criminal behaviour linked to genes

Y. Mallikarjun

HYDERABAD: Is criminal behaviour of a male also linked to his genes, apart from environmental factors?

The co-relation between them has been indicated by a collaborative study conducted by the Centre for Cellular and Molecular Biology, AP State Forensic Science Laboratory and Dr. Hari Singh Gour Vishwavidyalaya, Sagar, Madhya Pradesh.

While earlier studies had reported correlation between higher levels of testosterone (male sex hormone) with violent rape activities, this was the first study that associated reduced repeat lengths of DNA molecules – CAG (cytosine, adenine and guanine) in androgen receptor gene with violent criminal behaviour, said K. Thangaraj, one of the lead authors and senior scientist at CCMB. Androgen, the hormone required for male sexual development, mediates its functions through androgen receptor (AR). The AR gene plays a key role in the normal development of male sexual characters.

AR role

In the study which explored correlation between CAG repeat length in AR gene and criminal behaviour, the scientists analysed CAG repeat length in 645 men. As many as 241 of them were convicted for rape, 107 for murder, 26 for both murder and rape, while the remaining 271 men formed the control group.

It was found that there were significantly shorter CAG repeats in rapists (mean 18.44 repeats) and murderers (17.59) compared to the control men (21.19).

The criminals, who committed murder after rape had a far shorter (17.31 repeats) when compared to controls of those convicted of rape or murder alone.

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