Hereditary Allegories : A Study in Genetics

G & H : Smooth Ancestors

These twins were born to parents both having perfectly smooth, wrinkle-free brains. However, while Mouse H is smooth like its parents, Mouse G has a wrinkley, multiple-folded brain. According to Mendelian genetics, this points to a rarely expressed recessive gene inherited from an ancestor with a wrinkley brain.

Although a wrinkled cortex provides an increased cerebral capacity, the tendency among smooth-brained mice to mate only with other smooth-brains means that the recessive wrinkles will probably disappear within a few generations.

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Allegories