"....As for the resemblance of the child to its parents: If a man has sexual intercourse with his wife and gets discharge first, the child will resemble the father, and if the woman gets discharge first, the child will resemble her. ...."
Reference : Sahih al-Bukhari 3329 In-book reference : Book 60, Hadith 4
That would mean that if the man had an orgasm first, the child would resemble the man.
But that doesn't make sense, scientifically, it doesn't make any difference who comes first.