One upcoming film is Bill & Ted Face the Music.
It's the third instalment in a series that began in 1989 with Bill & Ted's Excellent Adventure came out in 1989 and was followed by Bill & Ted's Bogus Journey.in 1991.In earlier films, the teenaged title characters were played by Alex Winter and Keanu Reeves, both in their mid-20s at the time of the first two films.
Winter, who had previously appeared in a few films, notably The Lost Boys, went on to a prolific career in voiceovers and directing, mostly TV and documentaries. And Reeves - well, if you don't know what happened to him, what rock did you just crawl out from under, dude?
In the new film, Bill and Ted have their own kids. At least the guys have aged somewhat realistically as characters over the past three decades (the age gap doesn't matter now). Whether they've matured is, of course, another matter.
Casting children and teenagers is a tricky business. There are matters to consider such as acting ability and self-discipline during the long and sometimes tedious process of making a movie. After casting, there are laws governing the amount of time child actors can work on set and if they're of school age a certain amount of the day must be devoted to their education.
Often more than one baby plays an infant character. And newborns can be significantly larger in movies than in real life. Young kids are sometimes played by twins (enabling double the amount of work time). As kids get older, things get trickier: it's hard to sell an 18-year-old as a 10-year-old, no matter how great the talent.
From high school (which in the US begins in year 9), however, filmmakers often employ adult actors, who don't have the same limitations on their time as minors.
A certain amount of suspension of disbelief on the part of the audience is generally required for this "older" casting to work. Obviously some actors look younger than others, often for a long time (Leonardo DiCaprio comes to mind) and makeup and lighting as well as skilful acting help a lot.
But sometimes filmmakers really push it. In The Natural, Robert Redford starts the film as the main character, Roy Hobbs, at different ages, starting at age of 19. Redford was 48 at the time, old enough to be the main character's father, and no amount of makeup or lighting could conceal this distracting fact. Couldn't a young actor who resembled Redford have been found or was the star's vanity at play here?
Matt Damon was far too old to be playing Liberace's teenaged toyboy Scott Thorson in Behind the Candelabra. Damon is talented and fairly young looking, but in his 40s was more suited to being the father of an 18-year-old. Having a star like him - and Michael Douglas as Liberace - no doubt was crucial to getting the film made. And perhaps it was felt audiences would feel less uncomfortable with an older actor, and one who like Douglas was known as an overtly heterosexual married father.
Leslie Howard - in his 40s - and Norma Shearer - in her 30s - were cast as Romeo and Juliet (1936). Granted, the actors cast as Shakespeare's tragic lovers are usually a bit older than the 13 for her and some years later for him - partly to avoid ickiness, partly for stardom and talent. But to cast them with actors who would be more likely to play their parents is a stretch.
Grease also had some decidedly geriatric-looking teenagers. Olivia Newton-John (Sandy) was 29, John Travolta was 24, and Stockard Channing was 33 - old enough to be the mother of a teenager. Given the almost campy tone of the film, it didn't seem to matter, certainly not to audiences: Grease was a big hit.
Emma Thompson in her mid-30s was not an altogether convincing 19-year-old in Sense and Sensibility despite her acting talent, but she adapted Jane Austen's novel, so perhaps her casting was part of the deal.
Richard Linklater dealt with the issue of ageing in a possibly unique way: he filmed Boyhood periodically over 14 years with lead actor Ellar Coltrane ageing from seven to 19. It was risky - what if Coltrane died or quit, what if money ran out? - but worked out fine.
With older actors playing younger characters, often you just have to go with it and rely on the movie to sweep you along so you forget about such matters. That's Hollywood.