Separated at birth

When I lived in Germany 3 years ago there was an interesting statistic that one in seven German children were not fathered by the man they grow up calling 'Papa'. That's pretty high, but probably reasonable given that one in three married German women admit to cheating on their husbands (not sure what the ratio for men is, but it's probably in the same ballpark). No wonder Ralf married an American! As you can imagine, growing up with these statistics, Ralf took a good hard look at Leni when she was born until she started looking so identical to him that people on the street started commenting on it. No question about whose child Leni is - guess which one's Ralf?