Somewhere earlier on this thread, someone named Mary (I didn't include DIS ids on my list if names were given...DUH) posted that she's cruising with an 11 yo daughter (and a 9 yo and 12 yo)
Imgraciesmom has an 11 yo boy, and Sue136 has a 9 yo boy (no 10 yos, but 9 & 11 is pretty close).
One of Dawn 38's 5 yo twins is a girl, and there's someone named Maura who's sailing with her 5 yo daughter.
So fear not! You children will find friends. And my DS does not discriminate; he enjoys playing with boys and girls alike and also younger kids (he really likes playing with older kids too, but I don't think the feeling is very mutual!)
By the way, we're confirmed on Captain Marvin's!