Hi JessM, yes you are right - research tells us that 100% of abusers have suffered some sort of abuse or severe neglect themselves, and have lived in dysfunctional environements, but being abused doesn't mean they will go on to abuse themselves.
There are a few elderly sex offenders who also have some brain lesions, but these do not cause them to sexually abuse, however this brain damage can result in disinhibition and all control is lost as a result. Temporal lobe damage does not cause sexual offending - other parts of the brain have also been referred to, such as the amygdala - sexual disinhibition can occur with such damage, but not necessarily sexual offending/abuse of children.
The XYY chromosome was reputed to signify propensity to violence in men, but further research showed just as many non-violent men having the same chromosome.
Sexual offending is widely understood to be learned behaviour, and it is more entrenched in those offenders who have been corrupted as far as their sexual arousal and attraction becoming solely towards children - neither gender is immune from being targeted by paedophiles, many of whom see children androgenously - it is their lack of adult features that is attractive.
For every theory that sexual offending is caused by genes, chromosomes, alcohol, brain damage and so on, there is research that shows these theories have no foundation.