Saw bits of the first programme, but not watched since .. found it all a bit too slow for me. being a multiple, though not, we think, identical, I thought it might be interesting, but didn't find it particularly so. As for language learning, I'm more of the approach that we all learn differently, even twins etc, (the etc being multiples), and it's finding the approach that suits you is better than applying "twin" rules.
I do remember that at one time one of my sisters and I got the same score in an exam (the in-built ones rather than the statutory ones). The class all laughed, and jeered, until the teacher said, yes, but they did not get it it in the same way ... so pure luck we got the same points. I think it was in English rather than French though.
ex W1, via 47 and 11 and now [just] in 34, equidistant from Carcassonne, Narbonne and Béziers, where I hope we'll finally stay!!