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DNA

sequence

genomic imprinting

in a nutshell

inheritance

It showed that there was clearly more to inheritance than simply the coded sequence of DNA.
We then realized that we were dealing with what is now known as genomic imprinting. What genomic imprinting means is, in a nutshell, that genes have a memory of where they came from.
Something other than just the DNA was capable of moving between generations. It was a tantalizing glimpse into this unknown and unexpected world. A hidden layer acting on and able to directly control how our genes function. It meant that inheritance was not simply about which genes you inherited, but whether those genes were silenced, switched on or off.
And you can think of it as a, as a light switch. Switch on the gene, the light is shining, the gene is active, makes, makes a cell do a certain thing. Or the light switch is off, everything is dark, that gene is off. The switches remain on or remain off, and that gives the cells their identity.
The activity of genes was being controlled by a switch -- the attachment of a simple chemical which dictated whether the gene was switched on or off.

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