It's very simple; he's saying the problem goes back to elementary school. You need to plant the seed then to foster any meaningful amount of interest and engage

It's very simple; he's saying the problem goes back to elementary school. You need to plant the seed then to foster any meaningful amount of interest and engagement in computers and computer science. Since this is currently only really succeeding with boys, you need to re-examine what's being done and make sure that the seed is also planted for girls. The boys will be fine because clearly what's being done is already working for them, but as a group girls are clearly not being drawn into computer science education and so that's where the problem lies.