Our Boys Are Doing It!

A month ago a friend and I had quite a surprise when we discovered that our two sons, 11 and 12, have been having sex.
We both thought that they were too young to be sexually active as such, which apparently they are perfectly capable of being. Then of course immediately we wondered if this meant that our sons were gay, although we decided that it had far more to do with their just finding thjis fun as was well as convenient to do together than actually a sign of that.
The two of us are just unsure just what to do about this. We are aware that boys do things like this together in a perfectly normal and healthy way, and girls with other girls as well, so we are reluctant to say anything to them, and are thinking that perhaps it is just best if we let them continue, and accept it as a passing phase. Mostly we are just thankful that they are both male rather than male and female. Are there any other moms out there in a similar situation and how they handling it?