Artificial insemination would explain the whole immaculate conception story that Locke was told. If it was done without Emily's knowledge she may have believed it, and it could have caused a mental breakdown. Maybe Cooper was only conning Locke all along. Maybe he wasn't the biological father at all.....just preying on a donor he knew was a good match for him somehow, and just filled in the blanks and hired a woman to pretend to be the Mom.