There are support groups available. It takes another twin to really understand. Talking to other parents and other twins who have gone through it is the best thing to do. If you would like to contact me, you can do so through California State University at Fullerton. They don't for a number of reasons.
Little girls mature faster than little boys.
As the boys start to catch up, then that is different, but in the early years, they tend to go in different directions. One is always considered the prettier one. I think the best thing parents can do is look for the individual talents of each child and build them up. Keep in mind too that as kids get older, looks may play less of a role in social situations. So try to play up each childs' talents.