I wonder if there is any way to verify this about a French surgeon who is said to have made observations on the topic. The info does happen to correspond fairly well with what few studies we have on Asian men, and also white men, ...

Menopause and Menstruation and their Hormonal Manifestations
[abstract]
"The ethnographic record {e.g., A French Army Surgeon (1898/1972), a 30-year specialist in genitourinary diseases} makes reference to numerous anatomical distinctions which show a similar pattern of whites being between blacks and Orientals. These include the placement of female genitals (Orientals front and high; blacks back and low); angle and texture of erection (Orientals parallel to body and stiff, blacks at right angles to body and flexible); salient buttocks, breasts, and muscularity (Orientals least, blacks most); and size of genitalia (Orientals smallest, blacks largest). We averaged the ethnographic data on erect penis and found the means to approximate: Orientals, 4 to 5.5 in. in length and 1.25 in. in diameter; Caucasions, 5.5 to 6 in. in length and 1.5 in. in diameter; blacks, 6.25 to 8 in. in length and 2 in. in diameter. Women were proportionate to men, with Orientals having smaller vaginas and blacks larger ones, relative to Caucasians. Clitoral size differed in length: in European women, 1.2 in.; in African women, 2 in. variations were noted; in French West Indies, the size of the penis and vagina covaried with amount of black admixture"