I have read twins have their own language, these kids probably just don't want to talk to anyone other than one another.
;)
I know, too, simple, huh??
In many cases this is true. However, these two don't even talk to each other. There are also concerns about their motor skills (one can't drink from a cup, or pick up things with thumb and fingers - only with a closed fist grip). Hearbreaking, really.