Have you ever looked at a baby and commented, “He looks exactly like his daddy!”   And why not?  He is the genetic offspring, a chip off the old block, the spitting image of his father, right?  There’s more to it than that, so believes a new theory posed by Dr. Nicholas Christenfeld, a psychologist.  His theory holds that the father confers a genetic trait—face genes that make the baby’s face resemble his.  “While a mother can be quite sure that the baby is hers no matter what it looks like, the father cannot,” says Dr. Christenfeld.  He continues, “It should then be to a baby’s advantage to look like the father, to encourage paternal investment.”