Interview the baby alone if possible. If, however, both parents are present, say, "It looks like its mother." And, as an afterthought, "I think it has its father's elbows."  
If uncertain as to the infant's sex, try some such formula as, "He looks like her grandparents," or "She has his aunt's sweet disposition."
 
When the mother only is present, your situation is critical. Sigh deeply and admiringly, to imply that you wish you had a child like that. Don't commit yourself at all until she gives a lead.
 
When the father only is present, you may be a little reckless. Give the father a cigar............