The most common reactions to the news today that the minimum age to join G+ is now 13 or 14, depending on the country.

1. “Oh, great. Now Google+ is like the mall.”

2. “There goes the neighborhood.”

3. “You kids stay off my lawn!”

The previous age limit was 18. The 13-and-up limit brings Google+ in line with Facebook and other social networks. And it’s a good thing, too, for one very simple reason:

People choose their social network when they’re teenagers.

The current default is Facebook. A typical scenario is that people join social networks at around 12 or 13. By the time they’re adults, they’ve got connections, history and familiarity with their social network that’s hard to walk away from. So whatever social network people start with is probably the one they’ll stay with.

And I don’t know about you, but some of my favorite people are teens: nieces, nephews, cousins and family friends, for example.

I remember how uncomfortable I was on Facebook when some teenage family members started sharing pictures with their friends in mind, not really understanding that they were sharing with older relatives.

Google+’s new teen-only features announced by +Bradley Horowitz make sense, and bring clarity to young users about what they’re posting and to whom.

Google+’s circles are great for teens, who can share some types of content with just close friends and peers, and others with the larger circles of family friends and older relatives.

The Google+ of tomorrow will be populated by the teens of today. So this is good news.