In sheep, a white fleece is the result of a dominant gene that actively switches color production off - that is why most sheep are white. This means a black fleece in most sheep is recessive, so if a white ram and a white ewe are each heterozygous (have the black and white forms of the gene for fleece color), in about 25 per cent of cases they will produce a black lamb.
Photo from SWNS.
This is quite a rare occurrence though, and in most white sheep breeds only a few white sheep are heterozygous for black, so black lambs are usually much rarer than this. That is why this case is so special. Mrs Du Toit said: 'We have had 60 lambs this month and every single one of them is black but all of their parents are white.
'Usually you see just one black sheep in an entire flock and that's where you get the saying from, but all of ours have this jet black coat. It is amazing. We don't know why it has happened. When the first few were born we thought it was great but now lamb after lamb has come out black. We feel blessed. I love the color. People are stopping on the cycle path and in their cars to look at the lambs and ask us if they are a special kind of breed.'
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