This mother appears to be about to write a letter to her children.

People usually wait to talk about this crucial family matter — until it’s too late.

Inheritance is a touchy subject for a lot of families, one that neither the parents, children or other family members know how to bring up, new research finds. In fact, only 21% of children were told how much they’d receive, according to a survey of 2,700 adults by Ameriprise Financial, a Minneapolis-based financial services firm.

That lack of transparency about what’s left behind could put them in a sticky situation down the line, experts say. And it can lead to disappointment. “There’s clearly an opportunity for expectations to be out of line if they haven’t had a chance to talk to the family about it,” said Marcy Keckler, vice president of financial advice strategy at Ameriprise. “Expectations about inheritance often don’t match what happens.”

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The conversation around inheritance can cause arguments or familial tensions. Some 47% of millennials think there’s potential for conflicts when talking about inheritance, and 25% of Generation Xers and 17% of baby boomers agreed, the survey found. Boomers were the most confident of their family’s financial future, followed by millennials and lastly…