We detected the genetic sex and the occurrence of sex reversal in eight normal families and their male parents in the half-smooth tongue sole ( Günther) using the SSR female-specific marker scaffold 1128_343 and a gonad slice. The proportion of females in eight normal families (28, 30, 38, 39, 40, 44, 57, and 69) ranged from 37.93 to 55.00%. The genetic sex of four of the eight normal families (28, 39, 44, 57) was detected twice, and the proportion of femalesdid not exibit significant difference between two tests (>0.05). We detected both the genetic sex and physiological sex in four of the eight normal families (28, 39, 44, and 57) and in all the male parents. The proportion of physiological females ranged from 18.75%−46.88% among the four families, and was lower than the proportion of genetic females. Our results suggest there are inter-family differences in the proportion of females undergoing sex-reversal. The present study also suggests that a significant number of male parent fishes (28.42%) are neo-males. Our results suggest that sex reversal is a natural phenomenon in the half-smooth tongue sole breeding population. Furthermore, we reveal the pedigrees of different physiological spawner ratio have significant differences. Our observations provide a theoretical basis for developing methods to culturing families that have a high proportion of female larvae.