Even though it premiered over 30 years ago in 1987, Full House remains one of the most beloved sitcoms of the modern era of television. The series followed the lives of Danny Tanner and his three children, DJ, Stephanie, and Michelle; as well as his brother-in-law, Jesse Katsopolis, and his best friend, Joey Gladstone, as they all lived in the same crowded San Francisco home.

For eight years, the series was full of plenty of wholesome storylines, cheesy jokes, and meaningful speeches that were followed by a hug. But the series also had its fair share of blink and you miss it reveals, and a few key character changes, too. Here are ten hidden details you might never have noticed about the beloved characters.

Jesse’s Last Name Changed

It’s inevitable that details about characters will change as a series finds its footing and irons out some of the personalities and characteristics of its core characters. But it’s not often the case that a character’s name - and, as a result, their heritage - winds up being changed after a season has aired.

That’s exactly what happened on Full House, though. Jesse spent the first season of the series as Jesse Cochran, but following a request from John Stamos, the character was renamed Jesse Katsopolis in the second season, as a way of incorporating Stamos’ Greek background.

Danny’s Mother Changed

From the opening scenes of the pilot episode, and for another appearance early in the first season, Danny’s mother is portrayed as a much more straitlaced, prim and proper woman by actress Alice Hirson. Hirson is probably best known for her recurring role on the sitcom Ellen, where she played Ellen DeGeneres’s character’s mother.

But when Claire Tanner returned in the beloved third season episode “Granny Tanny,” she was now portrayed by the likewise beloved sitcom icon Doris Roberts, who would go on to play an even more beloved and well-known grandmother on the series Everybody Loves Raymond.

Jesse’s Mother Changed, Too

Danny’s mother wasn’t the only one who got a total makeover, though. In the first season episode “The Return of Grandma,” when Jesse was still Jesse Cochran, his mother, Irene Cochran, was much more stern and tough when she was portrayed by character actress Rhoda Gemignani.

But when Irene, now Irene Katsopolis, began to recur in the second season, she was now much warmer and loving, and a very doting grandmother, too. Irene would appear in some of the series’ best episodes when she was portrayed by Yvonne Wilder, who is perhaps best known for her role as Consuelo in West Side Story.

Stephanie Needs Glasses, But Then Doesn’t Wear Them

The season four episode “Stephanie Gets Framed” is notable for two reasons: it’s the episode where Stephanie finds out she needs glasses, and it’s the episode where the series crosses over with fellow TGIF series Family Matters. When Stephanie fears she’ll be teased for needing glasses, television’s resident nerd Steve Urkel gives her some much needed advice.

Though Stephanie winds up with glasses in the end of the episode, she is almost never seen wearing them again after the fact, which makes the very special message of this episode more than a little confusing.

Jesse’s Name Isn’t Really Jesse

Full House’s fifth season finds Jesse and Becky expecting twins, and going through every possible pregnancy scenario, including trying to decide on the perfect names. It’s during the naming process, however, that the series reveals something surprising - only to never touch on it again.

The fifth season episode “The Legend of Ranger Joe” includes a subplot that reveals Jesse’s birth name is actually Hermes, but he asked his parents to change it after he was mercilessly bullied as a kid.

Kimmy Has A Really Big Family

Fuller House might have been the first series to visually introduce a new member of the Gibbler family, in the form of Kimmy’s younger brother, Jimmy. But as the many seasons of Full House described it, the Gibbler family is even bigger than we now know.

The pilot episode of Full House finds DJ offhandedly commenting that Kimmy has three sisters, and still somehow has a room all on her own. Later on, her older, dim-witted brother, Garth, often winds up being involved in some of her harebrained schemes, even if he’s never seen.

Rebecca’s Family History Changed

When Rebecca is first introduced in the series, she talks often about her quaint farm life background in Nebraska, including raising and riding horses, and her close knit farmer family and quaint country cousins.

That story doesn’t fit the family we meet at all, however. When her parents arrive, they’re clearly wealthy and privileged, and not at all the humble farm folk. Similarly, her cousin and his wife and children are just as arrogant and rich. The lack of continuity is beyond confusing.

Danny’s Personality Changed

Hard as it might be to remember, there was once a time in the series when Danny Tanner wasn’t a totally obsessive, germphobic, self-professed neat freak. Though Danny spends much of the series obsessed with cleanliness, to the point that it’s not hard to believe he most likely had OCD, the earliest episodes of the show paint a very different story.

In the series’ first few episodes, the Tanner house is often a complete mess and in total disarray - to the point that Danny’s mother even intends to stay with the family as a live-in cleaning woman.

DJ Isn’t In Every Episode

As the oldest of the Tanner children, and one of the main characters in the series, it’s easy to understand that DJ winds up getting some of the more meaty storylines, out of the three children. But what might come as as a real surprise is the fact that DJ is actually missing for an entire episode - and no one seems to notice.

The sixth season episode “Subterranean Graduation Blues” finds the extended Tanner family stuck on a train en route to Jesse’s high school graduation. And without explanation, DJ is nowhere to be found.

Danny Was A Teen Dad

Full House is one of the most wholesome, family friendly sitcoms in television history. But the series’ entire premise is predicated on something decidedly not as G-rated: according to the characters’ ages, Danny Tanner became a father when he was a teenager.

In the first season, Danny turns 30 midway through the year, when DJ is already ten years old. This means, then, that Danny is 29 when DJ is ten, going on eleven, which means Danny and Pam had DJ when Danny was around 19 years old.