There is an anime called Sword Art Online (really good Id suggest you watch). The basic premise is in the not so distant future video games have become Virtual Reality, when you put a headset on your body goes into a coma like state as your mind enters the game. Of course their aren't older avatars and not too young so people will appear older or younger in the game. In the first episode something happens and their avatars turn into their real world counterparts so any little kid playing would basically ar to normal or ap (if they were old).
Ok back to the topic of the subject. The anime was divided into 2 series "Sword Art Online" and "Sword Art Online II".
In the third intro for the second we saw one of the characters and her twin as a baby then age to little kid, then to pre teen and then into teen (though the other twin disappears)https://www.youtube.com/watch?v=Gx0yvJ0Z1yY
Then in the 24th episode of Sword Art Online II (there are 25 episodes) called "The Dream Begins". Asuna (the main female character) convinces her strict mother to talk to her inside the game for 5 minutes. The mother reluctionally agrees so she enters it under Asuna sub account character (she has two depending on the situation) so the mother becomes an avatar in her 20s (give or take...though Asuna is a teenager)