The idea that a genetic syndrome is associated with certain behaviours is the subject of much research. 

‘Behavioural phenotype’ is the term used to describe a strong association between specific behaviours and a particular genetic syndrome. 

It is often assumed that because of this association, the behaviours arise from the genetic make-up of individuals with the syndrome.  Commonly accepted examples include self-injurious behaviour in Lesch-Nyhan syndrome, over-eating in Prader-Willi syndrome and repetitive hand movements in Rett syndrome.  However, whereas some people suggest that a biological mechanism underpins the behaviour, we make no assumption about the mechanism underpinning the link between behaviour and a given genetic syndrome.  Thus, behaviours seen commonly in particular groups may not necessarily be determined by the genetic make-up of the syndrome, but may be influenced by other factors.

It is important to remember two things:

1. Just because some behaviours are part of a behavioural phenotype does not mean they are inevitable or, in the case of behavioural difficulties, cannot be reduced.
2. Behavioural features that are associated with genetic syndromes do not define children and adults with this syndrome.  Children and adults with a genetic syndrome are people first and have more in common with other children and adults than they have difference.  The main task for us is to try and understand why particular features of a syndrome might be associated with behavioural difficulties and to take information from the broader literature on all people with intellectual disabilities and work out the extent to which this is applicable to people with a particular genetic syndrome.