Twins

[david-us.livejournal.com]

 I have identical twin boys. I was in a conversation with a Russian the other day and was trying to convey this when I realized that I really wasn't very confident in how to say this. 

I had a lot of words swimming in my head - but I wasn't sure what to say.

близнец?

And what's the plural of this? How would you convey that they are male twins as opposed to female twins? What if it was one of each gender?

What about ...

двойник/двойня ? 

Again, how is it best to convey the gender of the twins?

How would you say "fraternal twins", "Identical twins", "He is my twin brother."

Thanks!
 

David Emerling
Memphis, TN