At the age of 12, House started to become suspicious that John House was not his biological father as John was away when House was conceived and Gregory and John do not share several genetic features, particularly the relative size of their second toe. On the other hand Bell, a Unitarian minister and close family friend shares a birthmark with House. House was so certain of the relationship that he challenged his father about it the summer after Gregory turned 12. John didn't deny it, but stopped speaking to Gregory for three months.