In 1943, Curt Stern, a German scientist who immigrated to the United States before World War II, pointed out in a brief paper in Science that Weinberg's exposition was more comprehensive than Hardy's.
[2] Weinberg observed that proportions of homozygotes in familial studies of classic autosomal recessive genetic diseases generally exceed the expected Mendelian ratio of 1:4, and he explained how this is the result of ascertainment bias.
In his work with albino children, he recognized that in some families where both parents carry a recessive mutation, no disease occurs by chance.
He reasoned that many carrier couples were not being counted, and he demonstrated methods for correcting results to produce the expected Mendelian ratios.
By the same token, he recognized that ascertainment was responsible for a phenomenon known as anticipation, the tendency for a genetic disease to manifest earlier in life and with increased severity in later generations.
In 1889, he returned to Stuttgart, where he remained running a large practice as a gynecologist and obstetrician until he retired to Tübingen a few years before his death in 1937.