Genesis 9:22

‘And Ham, the father of Canaan, saw his father's nakedness, and told his brothers outside.'

The continual stress on Ham as the father of Canaan shows that by this time Canaan has been born. This event is thus some time after the end of the Flood. The phrase ‘saw his father's nakedness' may be a euphemism for something worse, and this may be the first recorded homosexual act (see Genesis 9:24). This would certainly help to explain the seriousness of the punishment. However the difference in attitude between Ham and his brothers is also drawn out. Ham was not to blame for finding his father naked, but he was to blame for not being discreet and dealing quietly with the situation. Instead he made a big thing of it. There was clearly something very unpleasant about his behaviour.