Here are the kids' stats along with the how they compare to others their age:
Sarah is 37in tall (41%) & weighs 32lbs (63%)
Jake is 36.75in tall (25%) & weighs 33lbs (64%)
Luke is 37in tall (31%) & weighs 34.5lbs (77%)
I think Luke must have been retaining water or something because he usually weighs less than Jake.