For other characters named Jeff or Jeffrey, see Jeffrey.
After Dr. House told Whitney she was pregnant (and being astounded that she hadn't figured it out herself), she tried to convince Geoff that, although they had never had sexual intercourse, the other sexual activity they had could have resulted in her pregnancy. She tried to enlist Dr. House in this, but he refused. Geoff insisted on a paternity test even though Dr. House tried to lie to get Whitney out of it by saying it would be dangerous to the fetus.
Instead, Dr. House faked the results to show that the fetus had only maternal DNA and was therefore the product of parthenogenesis or "virgin birth". As Geoff and Whitney were both devout Christians, he accepted the explanation and reconciled with Whitney.