Scott Huver The new hit ABC sitcom “Home Economics” centers on three siblings in dramatically different economic realities, and whenever a cast or crew member questions a comedic setup, they turn to co-creator Michael Colton, who based the series on the financial disparities within his own family.“We’ll say, ‘Would that really happen?’ and he’ll pull out a picture on his cellphone and say, ‘Yes, it did,’” chuckles star Topher Grace.Grace plays Colton’s avatar, the not-so-bestselling novelist