Slapstick of Another Kind (1982)

Caleb Swain and his wife Lutetia are a rich couple deemed to be the most beautiful of all the beautiful people by the press. This changes when Lutetia gives birth to oversize, deformed twins named Wilbur and Eliza. Unknown to them, the twins are really an alien brother-and-sister team implanted in Lutetia to solve the world's problems. When they are apart they are not much smarter than a potted plant, but together they are an intellectual force to be reckoned with. Their closeness is put to the test when a series of events threatens to keep the twins apart. Mixed in with all this is a miniaturized Chinese ambassador who needs the twins' help to make a deal for the sale of gravity.