Joyce Adler is the sister of Grace and Janet, and the youngest daughter of Martin and Bobbi Adler.
Biography
Described by Grace as "the heavy younger sister", Joyce is the youngest of the Adler sisters. Though she is mentioned several times through out the series, Joyce first appeared during the flashback episode Lows in the Mid-Eighties where she was still in high school and living with her parents in Schenectady. She is implied to be bitter and resentful of Grace probably due to her having a crush on Grace's then-boyfriend Will.[1]
In the present, Grace mentions that she binge eats when stressed, probably due to an eating disorder.[2]