A detailed discussion about family finance could prove to be worthwhile, given the strong likelihood that older parents and their adult children have conflicting expectations about issues such as elder care, retirement security and inheritance.

Survey results released by Fidelity Investments found family members frequently disagree when asked privately about these hard-to-discuss topics.

Key findings from the Boston-based financial services company include:

- Twenty-four percent of the adult children surveyed expected they will have to help their parents financially at some point, yet 97 percent of the parents don’t expect to need help.

- Nearly all of the older parents and their grown children - 97 percent - disagreed on whether a child will take care of the parents if they become ill. One reason for the nearly universal disagreement is the small number of families who discuss their expectations in a comprehensive way. Just 10 percent of the adult children believed the conversations they had were very detailed, and 63 percent of the children and parents disagreed on the level of detail they had covered to date.

- Adult children typically underestimate the value of their parents’ estate by more than $100,000 on average, in part because few families have a detailed discussion about how much might be passed down through inheritance. Older parents were more likely to believe a conversation had been detailed.

- Expectations differ as to how financially well-off older parents will be in retirement. Thirty-eight percent of children thought their parents will have a very comfortable lifestyle, while just 20 percent of the parents said that about their retirements.

Kathleen Murphy, Fidelity’s president of personal investing, said the need for families to discuss these issues is likely to grow as more baby boomers reach retirement age, and as life expectancies continue to increase.

“Getting more comfortable with these conversations is going to be really important,” Murphy said. “The burden only gets bigger.A conversation about the national economy can lead into a conversation about your personal economy,” she says. Avoiding the conversation means decisions are put off until there’s a family crisis, often resulting in sharp disagreements.

Lack of communication was a key theme in the survey findings. Sixty-eight percent of older parents said they were more comfortable talking about these matters to a third-party financial professional than they were with family members. That was the case for 60 percent of the adult children.

The lack of discussion contributed to differing views about how often older parents worry about their long-term financial security. Forty-six percent of adult children think their parents worry at least once a month, while just 32 percent of parents reported they worry that often.

Adult children may be more concerned about these issues than their parents because many are part of what’s known as the “Sandwich Generation,” middle-aged people trying to care for their elderly parents while also supporting their own children.

Such parents “may be grappling with planning for their own retirement, helping to fund a child’s college education and dealing with eldercare and retirement challenges with their parents as well,” Murphy says.