==And I reckon MtheGM knows that a blonde is unlikely to be heterozygous for melanin production in the skin; discussion of the improbability of a blonde participating in a true F1 cross (producing the required 1:2:1 ratios of homozygous "white":heterzygous khaki:homozygous black) is what gave the limerick its supposedly educative value.==

Of course — absorbed these indispensable facts with my mother's milk. Reckon on, Rowan... Not sure, mind, where you find a 'blonde' in the limerick under discussion. His colouring/complexion specified in versions quoted; but not hers...