For some 50 years my Jewish radar has served me faithfully. I've always been able to spot another Jew a mile away. Lately, though, I've noticed failures. The extent of decline, however, only recently became clear in an epiphany I call 'The Post-Ethnic Twilight Zone.' Before we enter, let me describe my once-formidable Jew-spotting powers.

They were formed from the mid-1950s through the early-'60s, in the chain of 'incorporated villages' entwining Long Island's Southern State Parkway. Boom times! Easy mortgages lured thousands of Jewish G.I.s and their families away from Brooklyn and Bronx apartments into suburban bungalows.

Jews, of course, weren't the only newly white ethnics abandoning the city to the not-yet or never-to-be-whites transforming New York's politics. The same flood brought thousands of Irish, Italian, Greek, and Slavic families who, like us, were only a generation or two removed from the immigration trauma. Wherever the tides dropped us, we rooted, blossoming overnight into suburbanites.

Superficially, our lifestyle resembles that of the Northern Europeans ' nominal Presbyterians, Methodists, and Lutherans ' whose mores were displayed in such venues as the 'Donna Reed Show,' 'Leave it to Beaver,' and 'My Three Sons.' But despite our common commitment to barbecues, station wagons, and lawn care, we knew we were Wholly Other from our neighbors.

The origins of our Otherness was no mystery. It was rooted in that barely understood grab-bag of life-transition rites and domestic customs we all call 'religion.' Unlike Protestant 'faith,' the 'religion' of Jews, Catholics, and Orthodox Christians wasn't ever a list of 'beliefs.' It was a package of language and food, gesture, personal style, and ' don't forget ' historical resentments that permeated one's being.

Such religion spoke to us at a level deeper than opinions about heaven and hell, or the meaning ' or lack thereof ' of poor Jesus pinned to his cross. Call it 'ethnicity' if you like. It distinguished Jews, Catholics, and Orthodox as communities separate both from each other, as well as from those Protestant aliens whose forms of sociability we all accepted as the norm.

The Jewish version of this religion enabled me, by the age of 8, to construe idiosyncrasies of posture, jacket style, and book-bag size into knowledge: typically, that the figure a half block away on a dark winter school morning was Jewish and, therefore, no real threat. Even if twice my size, I knew I could make him laugh by saying something filthy in Yiddish. And that would remind us of our solidarity against the true source of danger: namely, the Italian- and Irish-Catholic kids we labeled as 'Hoods' or 'Greasers.'

Possession of Jewish radar entailed near-perfection in the detection of goyim. Okay, there was the occasional red-haired freckled kid, like Ricky Wolinsky, who I mistook for an Irish shaygetz the morning his family moved in. But Mom knew better, informing me that Wolinsky is a 'nice Jewish name.' She proceeded to instruct me in the mysteries of Jewish family names, such as the rules that govern Markowitz's transformation into Marx, Marks and, even, Moore.

As for the nuances of Jewish manners, gaits, and faces, God only knows how I figured these things out. But I knew that no kid who'd had a Bar Mitzvah at Wolfie's would ever roll a pack of Camels into the short sleeve of his muscle shirt! Such Jimmy Cagney schtick was strictly for alumni of the local parish school, St. Catherine of Sienna. There the habited nuns hovered like birds of prey over the playground, nabbing young gangsters-in-training. These kids perfected a surliness that amazed us Jews when, in 9th grade, they entered North High, majoring in Auto Shop and Business Arts.

My radar was subtle. For example, what distinguishes your Jewish schlump from any other kid known, among the girls in the class, to suffer from a case of 'cooties'? The key is in the back seam of the trousers. If they'd been let out and resewn so that the darker fabric formed a V-shape against the more faded cloth, you had a Jewish schlump, like the unfortunately named Paul Sass.

Pubescent Jewish boys, you see, always gained their weight in the tush; goyim gained it in a manly boich overhanging the belt. The owner of a boich, of course, could still buy his skin-tight chinos off the rack, since the waistband needn't contain his belly; we broad-beamed Jewish boys, by contrast, were sent to the Husky Shop at Barney's Boys Town for our special needs.

So, you see, I was no amateur.

But now to the promised epiphany. The setting, as in all Twilight Zones, is innocent: in this case, through the portal of the men's room in the U-Village QFC. Notice a somewhat pudgy, 30ish young man of Asian ancestry ' we'll guess Chinese. He kneels in the disabled stall, balancing his equally Asian 3-year-old daughter on the commode.

Always the ethnologist, I am charmed and think, 'How East and West join in the humble, but universal, rites of fatherhood!'

At which moment I overhear this exchange in Seattle-accented American English:

'Come, Raizy, make pishy so Abba can take you to the Hanukkah store!'

'No! Raizy doesn't want the Hanukkah store! Raizy wants Baskin!!!!'

'But Sweetie, Abba is fleishig and can't have Baskin with Raizy!'

'BASKIN! BASKIN! BASKIN!'

'OK, as soon as Raizy makes pishy, Abba will watch Raizy have Baskin!'

Astounded, I reflected: How did East Asian Abba come to speak an American Ashkenazic patois tinged with neo-Orthodox overtones? Where's his yarmulke? Could any of this tableau have occurred without the preceding two generations of American Jewish post-ethnic assimilation? Is this where Jewish Long Island was headed the whole time I thought that me and mine were the providential goal of Jewish cultural evolution?

I have no answers. By the time I recovered, Raizy's pishy was finished. But one thing I know for sure: Jewish radar, Jaffee-style, is dead!

Come see Professor Martin Jaffee speak. 'Remember Amalek,' which will explore patterns of Judaic memory and the politics of contemporary Judaism'

on Wed., February 8, 7:30 p.m. at 220 Kane Hall on the University of Washington campus. Admission is free

and a reception will follow.