It seems to me that, in most of the cases where someone on TV ends up having twins, it’s a boy and a girl. (Okay, the only two that I can think of off the top of my head are Get Smart and The Cosby Show, which were 20 years apart, but it still seems to me to the “the rule” rather than “the exception”; maybe I am including already-born twins (e.g. Rugrats) and non-TV occurrences as well.)
How many instances are there of TV families having twins (or more) where all of the children are the same sex?
I can think of three: Mike’s three sons on My Three Sons, Mr. Kotter’s twin girls on Welcome Back, Kotter, and Ray’s twin sons on Everybody Loves Raymond. Of course, the first was in keeping with the show’s title, and the third is based on Ray Romano’s twin sons.
Sister Sister was about a set of twin sisters, and The Suite Life of Zack and Cody is about twin boys. The Patty Duke Show was of course about identical cousins, but Patty and Cathy’s fathers were twin brothers.
Any show that’s done an “evil twin” or twins-switching-places story presumably featured identical twins…if the characters are actually siblings. It’s fairly common to have characters who are physical doubles (coincidental look-alikes, clones, alternate universe counterparts, etc.) but not actual twins, though. Here’s the full list of twin-related TV Tropes.
On Xena most of the major characters encountered look-alikes at some point, but these usually weren’t their actual siblings. However, Joxer turned out to be one of a set of identical triplets. There was also an episode that featured a set of identical twin sisters (one good and one evil), and another episode where the mythical twin brothers Castor and Pollux appeared.
Not television, but if movies count then there’s any version of The Parent Trap and Fred and George from the Harry Potter series.
Probably because if you show identical twins, you’d almost need identical quads to play them. Most little kids on TV are played by twins, right? They want to reduce the working time for the kids, so they split the role. Identical quads are very, very rare. So it’s just easier to go with a set of twins that can’t be identical - boy/girl twins.
There were some direct to TV sequels to the original version, at least one of which had the Creel triplets (all girls) involved. One of them went on to appear in the last set of Saved By The Bell episodes (those weird ones without Kelly or Jesse), another of which went on to marry the infamous comic artist/writer Rob Liefeld.
The Saved By The Bell connection is kinda weird, since that show originally was another show starring Haley Mills (star of the Parent Trap and its sequels) as Zack Morris’s teacher, Miss Bliss.
How can I have forgotten Phoebe and Ursula Buffay from Friends/Mad About You? Forgetting that Friends ended with Monica and Chandler getting twins (one of each) is understandable. Phoebe also had her brother’s triplets: two girls and a boy.
Another example of identical cousins are Samantha and Serena from Bewitched.
Jeannie, from I Dream of Jeannie, had an evil twin named (drumroll please) Jeannie!
“Peanuts” and “The Simpsons” both have peripheral characters who are identical twin girls, but they are cartoons so using live actors isn’t an issue.
The original “Degrassi (Junior) High”, which aired in the late 1980s, had identical twin characters (Heather and Erika) who were played by identical twins. They had cameo roles in the updated series.
[ul]
[li]Carol Hathaway had twin girls on ER[/li][li]Charlotte King and Cooper Freedman had triplets on Private Practice, all girls[/li][li]I dunno the characters’ names, but over the summer one of the doctors on Night Shift and his wife had twin girls[/li][/ul]
I suspect that this would be incredibly difficult to do an accurate count on, but I think that the number of twins on American television shows as a proportion of all characters is significantly greater than in real life.