*Father - Grigory Vitalievich Khlopin (1863-1929).
*Mother - Ekaterina Alexandrovna, née Kavaderova (1865-1945) - a graduate of the Higher Womens Courses in St. Petersburg (verbal-historical and physical-mathematical faculties), was engaged in journalism. (at the time of G. V. Khlopins exile to the Urals in 1886), from 1905, when the Khlopins lived already in St. Petersburg, Ekaterina Alexandrovna was engaged in charity work. She died on the road during the re-evacuation of the State Radium University from Kazan to Leningrad.
**Brother - Nikolai Grigorievich Khlopin, a histologist.
Khlopin was first married to Nadezhda Pavlovna Annenkova (daughter of the Narodovtsy P. S. Annenkov[clarification]).
*A daughter (born 1913), whom they baptized in a church in Kuokkala.
*In 1920 he married Maria Alexandrovna Pasvik.