This week, how one of the worst ideas in science got a big push from a bad study… and intellectuals of the day lapped it up. We speak to science writer Carl Zimmer and Prof. J. David Smith, whose research helped get to the bottom of this disturbing story. UPDATE 05/25/18: This episode has been updated. A previous version said that the 'good' side of the Kallikak family included someone who had signed the Declaration of Independence. It now says that the 'good' Kallikak family member married into the family with the relative who signed the Declaration of Independence. Check out the full transcript here: http://bit.ly/2sak22y To find a list of our sponsors and show-related promo codes, go to gimlet.media/OurAdvertisers Selected readings: Carl Zimmer's book 'She Has Her Mother's Laugh' Henry Goddard’s book about the Kallikak familyJ. David Smith’s article on the truth about Emma’s familyThe sad story of Carrie Buck and forced sterilization  This episode was produced by senior producer Kaitlyn Sawrey, Wendy Zukerman, Romilla Karnick with help from Meryl Horn, Rose Rimler, and Shruti Ravindran. We’re edited by Blythe Terrell, extra editing help from Alex Blumberg and PJ Vogt. An extra thanks to Phoebe Flanagan as well as Emily Ulbricht for help with German translations. Fact checking by Michelle Harris and Meryl Horn. Mix and sound design by Emma Munger. Music written by Bobby Lord and Emma Munger. Thanks also to Professor Peter Visscher, the Zukerman Family and Joseph Lavelle Wilson.