Well you have to look at it case per case because I've seen teens that looked like 19 but where only 14, but also the other way 'round where girls at there 18 still looked like a 14 year old kid.
But by changing the setting, deciding on make-up or not, selecting the clothes, etc, you really have a lot of control on the finished product.
Let's start with some pictures out of a workshop where we worked with Charlotte and her younger brother Mathieu.
It was a sunny day, devil hour as they say. This translates into the worst conditions for us as photographers, hard contrast, hard shadows, oversaturated colors, etc... Unless you actually know what your doing it's a pretty hard getting some nice results.
There are several options, but when you look closer at it, it all boils down to "work with the light" or "work against the light". Most of the photographers will choose the work against the light and try to fill in the shadows with reflection or flashlight.
For this shot of Mathieu i worked with the light, I had Mathieu standing in the open shade of a building and the sun shined on the concrete floor behind mee which resulted in a warm reflection and very nice color temperature, It's pretty flat light but it's always flattering and works very well for kids
The next shot was also made by working "with the light", assistant holded a translucent sunscrim over the head of our 2 young models to soften out the harsh sunlight and another assitant throwed some light back in the composition using a big California bounce panel (Zebra Pro)
