What cable networks are “sister networks”?
I know Food and Cooking are sister networks, and A&E runs History, what about others?
There are whole extended families of cable networks.
Bravo, CNBC, E!, G4, Golf Channel, MSNBC, NBC Sports Network, Oxygen, Style Network, Syfy, Telemundo, USA, Universal HD, and Universal Sports are all a part of NBC/Universal.
Viacom owns MTV, VH1, LOGO, CMT, Spike, Nickelodeon, Comedy Central, and TV Land.
Discovery operates the Discovery Channel, Travel Channel, TLC, Animal Planet, Science Channel, Military Channel, and Investigation Discovery, or I.D. In addition, it is co-operator of OWN (Oprah Winfrey Network) and the Hub.
Turner Broadcasting owns TBS, TNT, CNN, Headline News, TruTV, the Cartoon Network, TCM, and Boomerang, among others.
The Disney Channel, ABC Family Channel, and ESPN are all part of Disney/ABC Television Group. They also own partial interest in A&E, the History Channel, and Lifetime.
Thanks cochrane! BTW, welcome back from the island! 
Thought Food owned Travel, due to crossover of talent appearing. (mostly 1 way)