Sentence:  Skeletal similarities are only part of the story Dr. Shubin wants to tell. He also looks at genetics, because our genes provide a historical record, just as fossils do. For instance, we have yolk-making genes, though they're no longer active, because some of our ancestors laid eggs. “We carry the genetic signature of our <WSD>eggy</WSD> past,” this accessible scientist says. 
Meaning of the word marked with <WSD> tags:  Of or relating to an egg or eggs.