Overweight Babies?

About a month ago, a co-worker of mine had a baby granddaughter and she weighed in at a whopping 9 Ilb 13 oz and yesterday another co-worker's wife just had a baby boy, are you ready for this...........................????? 10 lbs, 12 oz!! The first baby photos look like they are like 3 months old. I doubt any of the "newborn" infant clothes they received at the baby shower will even fit. I'm a mother of 2, my daughter was 5 lbs, 4 oz. My son was 6 lbs, 2 oz. These 2 babies above weighed twice as much as mine did. What makes some babies bigger than others? Is this normal for babies to be this big at birth? Needless to say, both mothers had an extremely hard time giving birth and I know one of them had to have a C-section.