Drop down menu showing without hovering

Hi, I recently starting working on a website with the twenty eleven theme and I notice that the drop down menu dosn’t work the way i remember it to be.
from what i can remember twenty eleven theme’s drop down menu (sub-page)was always hidden if im not mistaken and it was dropping only when hovering the parent page. From what i can see on the website im working and the preview of the twenty eleven theme, the sub-page is always showing without hovering the parent page.
Was it always like that and im just remembering it wrong?
and can anyone help me fix this on my website?
I would like to make the sub-page drop down only when hovering the parent page.