Large kid size is usually a good thing but doesn't necessarily transfer into large adults. So much factors into growing a goat regarding genetics, parasites, nutrition, disease, etc. thats its not practical to estimate the final weight based on kid size. Twins are generally smaller than a single kid at birth and triplets are generally smaller than twins but they all grow to be full size in the end. When selecting kids I look for long heavy boned legs, big ears and a big nose. Goats tend to grow into those things and I have found that they are pretty good indicators of a goat that is going be larger in size than its siblings.
Friendly and energetic are also important qualities to look for.
