Not much has been explored about Dr. Kaplan. In Young Avengers #7 his son Billy Kaplan ( Wiccan) and his team mate/boyfriend Teddy Altman ( Hulkling) tried to tell Billy's parents that they were super-heroes but Ms. Kaplan assumed that they were trying to tell them they were gay which Mr. and Mrs. Kaplan where fine with.
Mrs.Kaplan responded by saying, "We've always known." but Mr. Kaplan responded by saying "I didn't. Your mom had to tell me." Dr. Kaplan then welcome Teddy to the family.