These movies appeal to a wide audience. Adults & children can both watch these genres and enjoy. For example Toy Story 3 everybody wanted to buy a ticket an watch it and it was being advertised everywhere!
Thrillers take a low proportion of UK Box Office (only taking 4%) because there is not enough advertisement around thrillers. Also in my experience most people do not know the distinction between horror films and thrillers.
If you want to get a thriller for both genders, a horror thriller will do the trick as it is slap bang in the middle on the scale!
Most thrillers certificate are for an older audience so thrillers have already lost children for an audience.