Last Night's TV: Long Lost Family/ITV1<br />Secrets of the Arabian Nights/BBC4

The biggest surprise in Long Lost Family is that it's not been made before. Ancestry, investigation, lost relatives: it is, surely, a match made in wall-to-wall heaven. After all, these are the people who brought us Who Do You Think You Are?. This was but a moodboard away.

The format felt familiar before we'd even begun: Davina McCall, Nicky Campbell, a couple of willing volunteers on the hunt for missing loved ones destined to have their hopes satisfied by the magic of television. "This is the series that steps in to help, offering a last chance for people desperate to find long-lost family," said a twinkly eyed Davina.

So there was Jennifer, aged 66 and still looking for her twin sister. She found out she had one when a cousin revealed that her mother wasn't really her mother after all; her auntie was. She'd been adopted as a baby, and her sister given away. Ever since, she said, she'd been determined to track her sibling down. Knowing about her but not knowing her was, in her eyes, "torture". He daughter did her best to comfort her: "I reckon she's just like you. A little old lady with short hair."

Actually, she wasn't far wrong. Not on the little old lady front (I'm not sure 66 quite qualifies for that) but certainly on the just-like-you. Kathleen turned out to be very like Jennifer indeed: same hair, similar face ("bit fatter," pointed out Jen), same neighbourhood. She lives three miles away, and has done all her life. It is sort of remarkable: "Hasn't she seen me?" asked Kathleen, on hearing the news. Apparently not.

Of course, as well as the finding-out part, there was the telling-your-relative part. Kathleen had no idea she had a twin. If someone told me that, I'm not quite sure how I'd react, though if anything, I think I'd be a little underwhelmed. Not Kathleen, who gave a terrifically telegenic performance, tearing-up and ohmygoodnessing to high heaven. A reunion was arranged, and all went to plan. They left hand in hand. A similarly happy ending was engineered for Karen, whose hope of finding her dad – he cut off all contact with her mother on discovering the 19-year-old was pregnant – was realised when he turned up living happily in Canada. And whaddaya know? He's a family man now: children and grandchildren up to his eyeballs.

It was all very warm and fuzzy and just what you'd expect, apart from the presenters, who struck me as an odd duo. His connection is obvious – adopted at four days old – hers rather less so. Still, she's really rather good: none of the overgrown-yoof presenting she favours on Big Brother, much more concerned (grown-up) friend. I can't imagine this continuing for more than a couple of series – it's all a little one-trick: once you've got the hang of the tracking-down-strangers part, there's only so much to be astonished about. But, for the meantime, it ain't bad.

"This is real time travel," enthused Richard E Grant, as he clambered aboard a camel in the Egyptian Sahara. He did a lot of that last night: enthusing. In fact, the first half of Secrets of the Arabian Nights was pretty much just that. Grant, in various milieux, trying to drum up excitement: just look at this sand, just look at these walls et cetera et cetera.

And then, a good 20 minutes in, it all got rather good. We heard about Antoine Galland, the French translator who brought the word-of-mouth tales beloved by Middle Eastern nomads and recorded in One Thousand and One Nights, to the excitable attentions of 18th-century Parisians. We heard about the reaction when, two years later, the stories arrived in Great Britain: the fashions they inspired, the trend for being painted in so-called "Oriental" garb, the wonder at the tales' contrast with the popular fairy tales of the day. "Just the flying – no one had ever considered that," said Grant. And he was right: the idea of soaring through the skies, invested with the power of flight, was entirely novel. But look how much it crops up now: Wonder Woman, Superman, Harry Potter.

Not every reaction was positive. The stories were, in their original state, terribly racy indeed. Take this one – "The Porter and the Three Ladies of Baghdad". Not only do the eponymous four wind up naked, "kissing, toying, biting, handling, groping", but they perform a ritual of naming one another's, well, you know. It was enough to prompt the Earl of Shaftesbury to call for a ban, and more than enough for several publishers, who made sure to clean up the works before they hit the presses. The tales still cause problems today. When a publisher in Egypt released a complete collection recently, he received death threats.

Grant, throughout, made for an intriguing guide. He's so very actorly, so extremely posh-seeming, that it felt a bit like being returned to school and given a lesson by the dusty old history professor. That's not necessarily a bad thing – the traditionalism of the delivery rather suited the historicism of the subject matter – though it ensured the whole programme remained a rather esoteric affair, more fringe interest than anything else. Perhaps to compensate, Paul O'Grady put in an appearance, talking about his appearance in (what was presumably last year's Mayflower production of) Aladdin. It's all about dreams, he said, you can apply all sorts of interpretations. Try telling that old Earl of S.

a.jarvis@independent.co.uk; twitter.com/aliceazania