soap operas not just for girls

I have been thinking about this for a while now, and I was wondering why are "day time" tv shows called soap operas, but "Stargate" SG-1, Atlantis, which I might add have been on air for 10 years, is not considered a soap opera. I know so much about this not because I watch it, but Brian tivos it and every time he gets a chance he is glued to the tv, like right now for example. I am not complaining that he has a favorite show, and I am not a soap watcher myself, I just think it is funny that girl shows are soaps and boy show are not...just a thought!