adult shows on family channels

So I didnt have work yesterday came home and just relaxed and watched some tv. I was flipping through channels and started watching "That 70's Show" After the first one ended and the second one was about to start, there was a warning on the screen about the show containing adult material, sexuality and language and all that good stuff. I realized the show was coming on ABC Family. From what I remember ABC Family always shows Rated G shows such as re-runs of Full House, Sabrina the Teen Age Witch etc.

That 70's Show is all about sex, weed, drinking and etc and I strongly beleive that it should not be shown on a channel where kid shows come. When a child is watching tv and a simple warning which is just words with a pretty background in the back come on, he/she is not going to read the whole paragraph and most of the time if parents think their child is watching a good tv show appropriate for their child, the next show is not going to be completely opposite of that.

I feel as if some shows should just be limited to certain channels. Like tv shows that are rated above PG should not come on channels which also have shows that are rated G because then obviously a small child doesnt have the ability to distinguish from whats good for him/her and whats not.