All happy families resemble one another, each unhappy family is unhappy in its own way.
Все счастливые семьи похожи друг на друга, каждая несчастливая семья несчастлива по-своему.
Original text (Russian)
Notes from Wikiquote
Pt. I, ch. 1
Variants
s: Happy families are all alike; every unhappy family is unhappy in its own way.
All happy families resemble one another; every unhappy family is unhappy in its own way.