This story happened at the session of the Academy of Sciences of the
(former) USSR. The notorious agronomist Lysenko (founder of "creative
Darwinism") gave a talk on the inheritance of acquired traits. When his
report was over, the famous physicist Landau asked: - So, you argue that if
we will cut off the ear of a cow, and the ear of its offspring, and so on,
sooner or later the earless cows will start to be born? - Yes, that's
right. - Then, how you explain that the virgins still being born?