Adult children and their parents often aren't on the same page when it comes to discussing critical family financial topics, according to Fidelity Investments' inaugural Intra-Family Generations Study released today.

The study identified distinct disagreements and miscommunication between parents and their adult children on a range of sensitive family financial topics, including retirement planning, providing care for elderly parents and inheritance strategies. For instance, 97 percent of parents and children surveyed disagree on whether a child will take care of his or her parents if they become ill. Parents and their children also demonstrate a communication gap when talking about inheritance and estate planning, with many children underestimating the value of their parents' estate by an average of more than $100,000.

Adult siblings and their parents also come to loggerheads over parents' retirement readiness. Twenty-four percent of adult children surveyed said they'll need to financially help their parents in retirement while 97 percent of parents say they won't need any help.

A big reason for the current parent-adult children communication gap, say Fidelity officials, is that the two groups simply don't talk about these issues. When asked who they are comfortable with when talking about their financial situation, the study found that 68 percent of parents and 60 percent of their adult children would feel more comfortable discussing with a third-party financial professional than with each other.

"Whether it's a parent facing a shortfall in retirement income or an adult child weighing the tax implications of an inheritance, too often discussing these issues is considered taboo within families," Kathleen A. Murphy, president of personal investing at Fidelity Investments said in a statement. "But real emotional and financial consequences emerge when such conversations don't happen or lack sufficient depth."

Fidelity's study was conducted online by GfK Public Affairs and Corporate Communication from July 24 to August 29. Parents were at least 55 years of age, have an adult child older than 30, and have investable assets of at least $100,000. Adult children participants were at least 30 years of age and have money saved in an IRA, 401(k) or other investment account. In addition, they must have at least $10,000 saved.

-Jim McConville