And as our parents live longer — at least one member of a baby boomer couple will turn 88, according to Social Security data — a functional relationship is crucial. After all, Mom might show up with candy for a long time. How to cope?

“Nothing pushes your buttons quite like an offhand remark from your parents,” says Rachel Albert, 37, an Arlington mother, who has a good relationship with her mom. This is true throughout our lives but especially for new parents, who already might feel insecure or sensitive. This relationship particularly affects mothers and daughters because women still “tend to set the tone for the household,” says Judy Osborne, 72, a family therapist in Brookline and a grandmother. Depending how close you were with Mom pre-kids, she might feel quite comfortable keeping a running commentary, whether you like it or not.

Part of the tension stems from generational parenting differences.

“I think I arrive at the same conclusions as my parents, but in different ways,” says Albert. She points to independent play. Her mother thinks her son needs time alone, and she agrees. “It’s great for kids to have unstructured time. But in the past it used to happen because you had lots of kids to watch. Now you might arrive at this conclusion from another angle. ‘What does my son lack in his “portfolio’’ of experiences? I’m going to strategically go over here and leave him alone now!’ [This generation] is more deliberate, whereas before, things happened organically.”

Parents have different challenges these days, says grandmother Becky Sarah, 64, the Cambridge-based author of the forthcoming book, “Grandmothering: Real Life in Real Families.” There are increased economic pressures, media bombardment, and conflicting child-rearing philosophies that many boomers simply never contended with.

“We had Dr. Spock, and that’s about it,” one former stay-at-home mom, now a grandmother, tells me.

“We’re hyperaware, and [our mothers] can think it’s silly,” says Jamaica Plain mom Victoria Moore, 33, whose mother babysits regularly.

Adding to the friction is the sense that, when adult children parent differently than their own moms, it’s an implicit rebuke. “It immediately kicks up a bunch of insecurities, and it makes it hard to unravel whether your [choices] are based on your philosophies or a reaction to your own childhood,” says one mother.

Leah Klein, 38, a Cambridge mother of two, agrees: “Parenting is a way to fix your own childhood,” she says, even if it was a mostly happy one.

To some extent, grandparenting is a second chance, too. One 47-year-old Boston mother, who asked to remain nameless, is getting the silent treatment from her mom, who’s upset about the family’s religious choices.

“But I know she means well,” she quickly adds. “Some people never turn that switch off; they still think of their kids as a child. It comes from a place of wanting to help.”

Meanwhile, Moore’s mother has worried that she’s raising her son as a vegetarian, even though he’s just a typical picky toddler — and even though, as Moore points out, “there’s nothing wrong with vegetarianism.” (As a child, Moore was made to sit at the table and eat “every last bite.”)

Cambridge’s Karina Ku, 31, whose parents visit from China each year, says they sometimes overfeed her children in keeping with family traditions. They’ve also questioned her discipline choices as too lenient, which leads to squabbles.

It’s hard to feel confident when you’re still a child in someone else’s eyes — including your own. “I turn into a teenager when I fight with my mom,” Klein says, laughing. It’s easy to revert to old dynamics, even when you’re both well past puberty and nobody can take the car keys, and it goes both ways. Even the most easygoing grandmothers have trouble adjusting to the role of “parents of adults,” says Sarah. “Adults always think of their children as their children, even as grownups.” Meanwhile, “adult children have a hard time realizing that their parents are still growing and learning themselves” and that even the role of Nana takes adjustment.