What Families Are For : THE PERFECT FAMILY:<i> by Sharon Daley (E.P. Dutton: $18.95; 310 pp.; 0-525-246828-2) </i>

Picture perfect. Isn’t that the way we always want our lives to be? What happens when they don’t turn out that way?

Sharon Daley’s first novel, “The Perfect Family,� tackles this theme through the Gregorys of Santa Monica and how they individually recollect their lives as a family.

As the book starts, eldest child Judith--who is herself an attorney--is on trial for murdering her terminally ill mother, and she will do nothing to defend herself.

From these sensational beginnings, Daley moves us back to the end of World War II, those traditional times, when a young veteran with vague ambitions to become a writer falls in love with a beautiful but taciturn shop girl. Robert and Margaret Gregory had high expectations for their life together.

And why not? Clean-cut, clear-eyed and sandy-haired Robert resembles Van Johnson, which puts him at the head of the good-looks pack. Margaret loves him unconditionally and even subverts her own position with their children, as they arrive, by advising them to “ask your father� when they come to her with their questions. The children think she’s stupid, but learn much differently as they mature and see their mother as probably the wisest of all of them.

The three youngsters are, of course, bright and attractive. Picture perfect. There’s no reason why they shouldn’t reach whatever star they’ve set their hearts on.

But then the Vietnam War arrives. And everything changes. The family especially changes, because old values are at war with new ones.

Take beautiful, blond Judith, for example. As a child she worships her father as he worships her. She’s a champion swimmer, a high achiever everywhere. She makes him proud. And then she wins a scholarship to Berkeley where she falls in love with a student radical, comes home in her anti-Establishment garb, uses the F word to her father and has a baby without getting married. Her father, hurt and confused, refuses to have anything to do with her.

Shy and insecure, Christine is the beautiful brunet daughter who hates and envies Judith. And yet it is Christine who keeps her virtue and even finds a man--a soldier about to ship out to Vietnam--who wants to marry her, which, she reminds her sister in one vicious scene, is more than Judith was able to do.

Finally, there’s Eddie, the youngest, brightest and most ignored of the children. Nobody understands Eddie, who from the time he is a little boy always seems to know just what’s going on with his family. Unfortunately, no one seems to hear him until it’s almost too late.

Mother Margaret remains obsessively protective of her family--her husband in particular, so much so that she is fiercely critical of the children when they seem not to understand him.

Of course she hopes that all their dreams come true, but when they don’t, she’s not undone. She’s not surprised. She’s a realist. What she does insist on is unfailing mutual support. “That’s what families are for,� she says sternly. Love is not the answer to Margaret; allegiance is.

The Rashomon technique is somewhat confusing, and the dialogue sometimes sounds terribly artificial, but what comes through very clearly is the unrealistic and often damaging nature of family expectations.