It’s hard to tell one nanny from another

If every unhappy family is unhappy in its own special way, the combined example of ABC’s “Supernanny,” which premieres tonight, and Fox’s “Nanny 911” (on break but with new episodes coming) suggest that all unhappy families dominated by small, screaming children are remarkably similar.

In each of these behavioral-makeover shows, an experienced child-care professional comes into a domestic madhouse to set things right. These households -- as edited for broadcast, at least -- are so insanely out of control, so mired in daily wars of attrition, so totally “Lord of the Flies” that once you sit down to watch either show, it’s hard to leave. You want the screaming to stop, and so you hang around until it does. (You can be assured it will: Reality TV needs winners -- even more than it needs losers.)

The success of the original “Supernanny” in Britain (its star, Jo Frost, also stars in the American series) and the respectable ratings “Nanny 911” has posted for Fox suggest that many people are willing to take this ride over and over again. It’s proven fun, looking in on other people’s disasters; it makes us feel better about our own. But screaming children are screaming children, even coming off a television, and I can see a fatigue factor possibly setting in.

The modern American nanny is a different spoonful of sugar, in-home day care for those who can afford it. They are employees and not always trusted employees. (Witness the nannycam.) They are placeholders, not child-rearers. Nor are they your grandmother’s nanny -- you will not be seeing any corporal punishment or castor oil. Lovely, familiar “Mary Poppins” is the obvious touchstone -- Fox’s nannies wear the British nanny cape and cap and have those cute accents -- but actually this is “Mary Poppins” crossed with “The Exorcist,” children kicking and screaming as the demons fight vainly for control. The power of Frost’s Naughty Stool compels you!

Fox created “Nanny 911” (with Britain’s Granada television) after it lost out to ABC in a bidding war for “Supernanny.” The two shows are essentially the same, except for a little windowdressing and a slight difference in tone. Fox characteristically emphasizes the chaos; the ABC series is more cheerful and clearer about processes and solutions. But they are the same. “Nanny 911” adds a short preamble, set at thatched-roof Nanny Central, where head nanny Lilian -- she’s worked for royalty! -- decides, or pretends to decide, which of three younger nannies (Deb, Yvonne or Stella) will best suit the week’s case. It also applies the narrative pressure of getting the kids ready for some party or public event, while “Supernanny” looks back in to see how they’ve been getting on in Frost’s absence.

Otherwise, they tell identical stories: Nanny arrives (by London taxi in “Supernanny”), diagnoses family, makes plan; haggard parents shift blame, express doubt; nanny demonstrates appropriate child-control techniques, with astonishing success; parents unsuccessfully try it for themselves as nanny lifts eyebrows; nanny gives additional training (the best part of tonight’s “Supernanny” is when Frost teaches the mother to speak expressively), which leads to a happy ending, hugs and kisses all round. (It is exactly the narrative progression of “What Not to Wear.”)

It’s all about having a few rules, which from the outside seem utterly self-evident. The parents are told to have a daily routine, get organized, be consistent, be firm, stay calm, pay attention, be engaged. (The adults are being made over no less than the kids.) The children’s side is simpler: no hitting, no biting, no screaming, no running around in the supermarket pulling food off the shelves when mommy’s trying to shop, please.

If those series make you feel that it takes an Englishwoman to raise a family, and that all British children must therefore be good, you might check out “Brat Camp,” an ongoing ABC Family documentary in which six extremely troubled British teens are packed off to an American “behavior camp.” (It airs tonight opposite “Supernanny,” unfortunately.) It’s “The Real World: The Middle of Nowhere,” as the kids -- and for all their bluster, and sad experience, they’re definitely kids -- are stripped of their cigarettes, piercings and possessions and sent off into the snowy wilds of Utah to face themselves. It’s highly engaging, if more than a little creepy.

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‘Supernanny’

Where: ABC

When: 10 to 11 p.m.

Rating: TV-PG (may be unsuitable for young children)

Jo Frost...Nanny

Barbara Jeans... mother (self)

Dave Jeans...father (self)

Andra Jeans...child (self)

Jessie Jeans... child (self)

Leah Jeans...child (self)

Executive producers Nick Powell and Craig Armstrong. Creator Nick Powell.