Even after Anderson Cooper and his mother, Gloria Vanderbilt, wrote a book and starred in an upcoming HBO documentary together, Vanderbilt can still casually drop knowledge about herself that will literally blow Cooper's mind, such as the lesbian relationship she had in her youth. In an interview with People, you can watch Cooper's stunned reaction to hearing his mom's big reveal.

Vanderbilt details the fling, which happened when she was 13.

Cynthia, her name was, and she came once to visit my aunt in New York on holiday​. We had this sort of lesbian relationship and it felt so great. It felt so good and yet I thought, 'There's something about this,' and this is before the thing I knew about my mother. I thought, 'No, this is something that's not really what I want.' It was very brief. 

I think almost everybody goes through at one point … of course, the thing is, now we realize there's no difference. Love is love​.​​

Sources: People