At what age do kids grow out of sleeping together in the same bed and in the same room?

I don’t have my own kids, but my sister asked me to watch their teens while they went on a vacation. For the entire two weeks I spent watching their teens, I notified my nephews 15 and 16, and my niece 13 still sleep together. They have their own room, but I’ve seen the boys woke up from her room or she woke up from their room. I couldn’t have swear they were taking a bath one morning together.

At what age do kids grow out of sleeping together in the same bed and in the same room?
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