Look what we can do

Yes, that's Matthew carrying Renee.  She tried to carry him, but at 4 lbs and 2 inches shorter, she's at a disadvantage.

Matthew is all muscle, he has abs and biceps.  Renee is lean and has a defined waist.  No baby fat left anywhere, except their hands.

As for Samuel's physique, he is tall and skinny, and he can carry either Matthew or Renee.  Much as they try they can't carry him.