Like all new parents, Arthur Zey and his partner Chase Popp think their one-month-old son Dax is the most perfect baby in the world. They glow with pride when they boast about his good health, his happy demeanor and even his lack of diaper rash. But unlike most parents, Zey and Popp don't attribute their son's excellent temperament to their paternal instincts alone. In March last year, they had a choice of six embryos created by Zey's sperm and a donor's eggs to implant into a surrogate mother. Genetic analysis gave them predictions for the future heights, IQs and multiple…