Documentaries referenced in the episode:

The Twinning Reaction, directed by Lori Shinseki - streaming on Tubi and available with a Youtube Premium subscription

Three Identical Strangers, directed by Tim Wardle - streaming on Hulu and for rent on Amazon Prime

Sources:

https://www.medpagetoday.com/psychiatry/generalpsychiatry/80829#:~:text=In%20the%201960s%2C%20clinical%20psychiatrist,a%20new%20tab%20or%20window.

https://yaledailynews.com/blog/2018/10/01/records-from-controversial-twin-study-sealed-at-yale-until-2065/

https://www.cbc.ca/passionateeye/episodes/the-twinning-reaction

https://en.wikipedia.org/wiki/Three_Identical_Strangers

https://archives.yale.edu/repositories/12/resources/3434