You figured it would always be this way — you, all your brothers and sisters plus their kids, gathering for holidays or summer barbecues much the way you did when your parents were alive.

But without your dad, who died a dozen years ago, or your mom, who passed away last year, such sibling gatherings have dwindled. You barely talk to your brother. Your sisters, once in awhile.

Blame some of this on the normal changes in a family's dynamic that come with high school, college, marriages and household moves. Usually a family can weather what Philadelphia psychologist Marjory Levitt calls this "development arc in sibling relationships."

But sometimes, it doesn't. If the deceased parent was the glue holding the family together, which may come as a shock to some siblings who never realized a parent played that role, how each family navigates this new relationship territory is "infinitely variable," says Levitt.

"There is no one resolution or lack of resolution. And sometimes what looks like an idyllic resolution after the loss of parents turns sour. Sometimes there are latent jealousies and unresolved conflicts," says Levitt, an associate professor in Temple University's department of psychological, organizational and leadership studies in education. "And one sibling or more than one sibling can carry a sense of injustice about how they were treated.

"It's complicated. I counsel siblings, and it can really be unbelievable. All of a sudden there are 3-year-olds in the room. They are all dressed up and they drive cars, but the conflicts are ancient."

Many kinds of issues

Such sibling squabbling is not the same as sibling rivalries over who's better at basketball or Scrabble, says New York psychotherapist Jeanne Safer. It's sibling strife.

"Sibling strife is the conflict that goes on into adulthood. It usually has to do with parental preferences and favoritism," says Safer, the author of "Cain's Legacy: Liberating Siblings From a Lifetime of Rage, Shame, Secrecy and Regret" (Basic Books). "That sets up often terrible things going on between siblings later in life. You know the 'Mom loves you best' thing? People don't get over this at the age of 80, long after Mom is dead.

"Families are mixed bags. You're very lucky if you have a sibling that's a soul mate," says Safer. "It's not all that common, and you should treasure it."

The longest connection

"Those are the people you knew before you knew who you were. You have a certain visceral relationship, an awareness of each other," says Levitt, who co-wrote "Sibling Revelry: 8 Steps to Successful Adult Sibling Relationships" (Dell Trade) with her own siblings, Jo Ann Levitt and Joel Levitt. "You have a blend of personalities and experiences that are harmonious for the most part. Or at least you have a backlog of experience that allows you to have a certain tolerance for the irritating quirks of your siblings.

"It's from your siblings that you learn how to relate to other human beings."

And, the Levitts write, it is usually "our longest-lived relationship."

Yet the death of that parent who held the family together — coupled with things like trusts and estates — can strain or even break sibling relationships.

"For some people," Levitt adds, "struggling for the love of a sibling can be a cornerstone of psychological distress."

It need not be, if the will to reconnect is there, says Safer. "That would require somebody to say, 'Look, the holidays are coming. I'm uncomfortable about it. We haven't ever really gotten along. Can we talk this out?'

"It is quite possible to do it if you have goodwill — without it, you can forget it."

Of course, how the sibling relationship plays out is as varied as the players. Sisters are historically the source of ongoing sibling connections, but brothers may step up as well. Yet, Levitt reminds, "If you have a pack of brothers, you could find that they really don't keep in touch or they keep in touch in a way that looks like not keeping in touch. For them, it's 'Oh, no, we're close' — and maybe they see each other every two years."

"Problems with siblings are one of the biggest regrets among older adults," says Safer. "Even if we never see them again, which sometimes is the right thing to do if you do it in a mindful way, they exist within us."

Adds Levitt, "If there's a reluctant sibling, for example, I wouldn't ever stop inviting them even if they never came. And sometimes, even in a later age, people will outgrow their resentments and there will be a reconciliation. As long as we're breathing, we can resolve whatever there is to resolve."

But there may be limitations.

"There's a certain amount of grieving that one has to do for things that never have been and never will be, that not everything is fixable in the family and the sibling relationship," says Safer. "Some resentments are just too deep to get over."

"There are some sibling relationships that really are toxic and that are better left alone," says Levitt. "Apart from those, it's an absolutely irreplaceable connection and, for me, I would go as far as I could to maintain the connection."

Would you ever give up? Only when, Levitt says, "you have evidence that your suffering is greater than the possibility of reward."

Reaching out to connect

Safer offers a few steps toward reconnecting with an estranged sibling:

After parents are gone, people need to first "work through sibling relationships within themselves — whether they ever talk to the siblings again or not."

Questions to ask: "Why do I want to do this? Is it for Mom and Dad? Is this because maybe I feel like there's something to this person? Is this for my children or their children?"

Think about how your sibling sees their childhood experiences. Ask yourself: "How does my sibling see our family and me? Who is this person, independent of my relationship with them? Who are they as a friend, parent, spouse, professional?"

"Realize this person probably has a lot of resentment about stuff you don't even know about and in different ways than you think."

Don't e-mail. She recommends a handwritten letter or phone call to say, " 'I'd like us to talk about some of the things that might have gone wrong when we were kids so we can have a better relationship now that Mom and Dad are gone.' Direct. Straightforward. And you have to be willing for your sibling to say no."

If they say yes, listen and acknowledge what they're saying.