One recent episode I particularly enjoyed was on military dolphins. I'd like to hear an equally good one on
identical twins.
I haven't hunted seriously for popular literature on this fascinating subject, but it clearly is an ideological minefield, much like "intelligence" testing. The
Wikipedia article on twin studies deals with methodology, not (un/)scientific results. All I really "know" about it is the stuff we've all been hearing on talkshows: how twins seperated at birth marry similar partners with matching first names, etc. It would be interesting to know how far the similarities really go, shaky statistics and media hype aside. Twin research and their alleged similarities are historically regarded as arrows in the quiver of nature versus nurture, also tainted as racist and immoral by Mengele's experiments in concentration camps.
And there is good movie/novel that just brought me onto this theme -
The Prestige. Btw, the book by Christopher Priest has a good twist at the end that isn't in the movie...