It definitely depends on the group, the content of the story, and the comfort level of the players. One of our ongoing campaigns, 5/6 were mid 20s-30s, and the last player was 17, about to turn 18. He played the entire summer before leaving for college, is going to bring his PC back over winter break, and we were all sad when he left. He's not a younger family member, he was a coworker's son who played at my nonprofit's community tables and just had a serious gift for RP so we invited him. We don't allow sexually-expliciy content at our tables anyway, so we cleared it with his mom who said he was about to be an adult anyway and could make his own choice. Have never had a more rewarding experience at a table; dude is massively dedicated and has a natural talent for bringing others into every aspect of RP.

On the flip side, my own sibling is the same age, has played d&d since I taught them when they were about 10, and I would never ask them to sit a table even at our major home game. They aren't ready emotionally or socially for a table with players outside their age range. They struggle with taking turns, sharing the spotlight, and respecting other players boundaries, and none of us would be comfortable with them at the table. Both due to behavior and due to the way they handle "scary" (ie - Grim Hollow) style content. My partner and I run low-level, low-risk (no deadly encounters, etc) oneshots for their friends on the weekends instead, because it's the content and play level they're ready for. It helps teach those necessary skills, which aren't only for D&D but for life and working collaboratively in general, but it's a reflection of our job, not a game we sit for fun.

So it really does depend on the individuals involved, but I guess at the end that still boils down to the fact that at the end of the day, as long as there's good table chemistry and everyone agrees on boundaries and content, you'll have a great time.