Diane founded Cullinan Properties, Ltd. in 1988 after being in the real estate business since 1981. Her vision and commitment have led to successful Cullinan projects throughout the Midwest, Texas and Southeast. Diane is married to Doug Oberhelman and has four grown children: Kathleen Cullinan Brill, Maureen Cullinan Bennett, Alison Cullinan Unkovich, and Allen Cullinan. Doug is the recently retired Chairman and CEO of Caterpillar Inc. He currently serves on many outside boards and is Chairman for DDI, an investment firm managed by Doug and Diane. They have 12 grandchildren.