R and G are genetically idential. No dispute about that. We’ve been there, had the DNA test done. However, R is definitely right-handed and G appears to be left-handed – or at least, she seems to favour her left hand more for tasks like drawing. Dh and I are both right-handed and so we naturally give things to the girls from our right to their right and we’ve noticed that G usually swaps the item into her left hand.
I need to do some detailed research on this but a very quick trawl reveals that 20% of ID twins have one right-handed twin and one left-handed twin – I’m fairly confident that I can find some more detailed research on this subject so I’ll do a thorough literature search soon (you can keep the girl out of the library…) but it’s another fascinating twist in our twin story.